Delete unpin_impl.rs UI test temporarily

This test is affected by an ICE in nightly-2022-06-04.
rust-lang/rust#97698

Minimized repro:

    trait Ambiguous<A> {
        fn method() {}
    }

    struct One;
    struct Two;
    struct Struct;

    impl Ambiguous<One> for Struct {}
    impl Ambiguous<Two> for Struct {}

    fn main() {
        <Struct as Ambiguous<_>>::method();
    }

Correct error in nightly-2022-06-03:

    error[E0282]: type annotations needed
      --> src/main.rs:13:26
       |
    13 |     <Struct as Ambiguous<_>>::method();
       |                          ^ cannot infer type

    error[E0283]: type annotations needed
      --> src/main.rs:13:5
       |
    13 |     <Struct as Ambiguous<_>>::method();
       |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot infer type
       |
    note: multiple `impl`s satisfying `Struct: Ambiguous<_>` found
      --> src/main.rs:9:1
       |
    9  | impl Ambiguous<One> for Struct {}
       | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    10 | impl Ambiguous<Two> for Struct {}
       | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

ICE in nightly-2022-06-04:

    thread 'rustc' panicked at 'range end index 2 out of range for slice of length 1', library/core/src/slice/index.rs:73:5
    stack backtrace:
      16:     0x7f4cccefd816 - core::slice::index::slice_end_index_len_fail_rt::h04ca4b0b6ddf070e
      17:     0x7f4ccceef707 - core::ops::function::FnOnce::call_once::hb4cbec441e0e0d97
      18:     0x7f4cccef6516 - core::intrinsics::const_eval_select::h2fab5eaa67d7a905
      19:     0x7f4ccce67556 - core::slice::index::slice_end_index_len_fail::ha1557d304be1c61e
      20:     0x7f4cce5ea20f - <rustc_infer[9b42245fee805938]::infer::error_reporting::need_type_info::FindInferSourceVisitor as rustc_hir[5dbb21eaf9590c92]::intravisit::Visitor>::visit_expr
      21:     0x7f4cce5e8edc - <rustc_infer[9b42245fee805938]::infer::error_reporting::need_type_info::FindInferSourceVisitor as rustc_hir[5dbb21eaf9590c92]::intravisit::Visitor>::visit_expr
      22:     0x7f4cce5fbe37 - rustc_hir[5dbb21eaf9590c92]::intravisit::walk_block::<rustc_infer[9b42245fee805938]::infer::error_reporting::need_type_info::FindInferSourceVisitor>
      23:     0x7f4cce5e8eee - <rustc_infer[9b42245fee805938]::infer::error_reporting::need_type_info::FindInferSourceVisitor as rustc_hir[5dbb21eaf9590c92]::intravisit::Visitor>::visit_expr
      24:     0x7f4cce5a1714 - <rustc_infer[9b42245fee805938]::infer::InferCtxt>::emit_inference_failure_err
      25:     0x7f4cce4f32bb - <rustc_infer[9b42245fee805938]::infer::InferCtxt as rustc_trait_selection[af2ed82902f8af73]::traits::error_reporting::InferCtxtPrivExt>::maybe_report_ambiguity
      26:     0x7f4cce4e6f87 - <rustc_infer[9b42245fee805938]::infer::InferCtxt as rustc_trait_selection[af2ed82902f8af73]::traits::error_reporting::InferCtxtExt>::report_fulfillment_errors
      27:     0x7f4ccec3fcb4 - <rustc_infer[9b42245fee805938]::infer::InferCtxtBuilder>::enter::<&rustc_middle[c4bb946b42085c78]::ty::context::TypeckResults, <rustc_typeck[4b1a1a7c06e44333]::check::inherited::InheritedBuilder>::enter<rustc_typeck[4b1a1a7c06e44333]::check::typeck_with_fallback<rustc_typeck[4b1a1a7c06e44333]::check::typeck::{closure#0}>::{closure#1}, &rustc_middle[c4bb946b42085c78]::ty::context::TypeckResults>::{closure#0}>
      28:     0x7f4ccebd170a - rustc_typeck[4b1a1a7c06e44333]::check::typeck
      29:     0x7f4ccfccf5f0 - <rustc_query_system[a1cbf340ec6d6f93]::dep_graph::graph::DepGraph<rustc_middle[c4bb946b42085c78]::dep_graph::dep_node::DepKind>>::with_task::<rustc_middle[c4bb946b42085c78]::ty::context::TyCtxt, rustc_span[c774ced8c61a5d44]::def_id::LocalDefId, &rustc_middle[c4bb946b42085c78]::ty::context::TypeckResults>
      30:     0x7f4ccf1f8380 - rustc_query_system[a1cbf340ec6d6f93]::query::plumbing::try_execute_query::<rustc_query_impl[f03dd36fb3d62396]::plumbing::QueryCtxt, rustc_query_system[a1cbf340ec6d6f93]::query::caches::DefaultCache<rustc_span[c774ced8c61a5d44]::def_id::LocalDefId, &rustc_middle[c4bb946b42085c78]::ty::context::TypeckResults>>
      31:     0x7f4ccf123c0e - <rustc_query_impl[f03dd36fb3d62396]::Queries as rustc_middle[c4bb946b42085c78]::ty::query::QueryEngine>::typeck
      32:     0x7f4ccec91708 - <rustc_middle[c4bb946b42085c78]::hir::map::Map>::par_body_owners::<rustc_typeck[4b1a1a7c06e44333]::check::typeck_item_bodies::{closure#0}>
      33:     0x7f4ccfa8e18c - rustc_typeck[4b1a1a7c06e44333]::check::typeck_item_bodies
      34:     0x7f4ccfcee823 - <rustc_query_system[a1cbf340ec6d6f93]::dep_graph::graph::DepGraph<rustc_middle[c4bb946b42085c78]::dep_graph::dep_node::DepKind>>::with_task::<rustc_middle[c4bb946b42085c78]::ty::context::TyCtxt, (), ()>
      35:     0x7f4ccfd991d5 - rustc_query_system[a1cbf340ec6d6f93]::query::plumbing::try_execute_query::<rustc_query_impl[f03dd36fb3d62396]::plumbing::QueryCtxt, rustc_query_system[a1cbf340ec6d6f93]::query::caches::DefaultCache<(), ()>>
      36:     0x7f4ccfdc3331 - rustc_query_system[a1cbf340ec6d6f93]::query::plumbing::get_query::<rustc_query_impl[f03dd36fb3d62396]::queries::typeck_item_bodies, rustc_query_impl[f03dd36fb3d62396]::plumbing::QueryCtxt>
      37:     0x7f4ccfac4473 - <rustc_session[d1b76e352c1a3b5b]::session::Session>::time::<(), rustc_typeck[4b1a1a7c06e44333]::check_crate::{closure#7}>
      38:     0x7f4ccfab109b - rustc_typeck[4b1a1a7c06e44333]::check_crate
      39:     0x7f4ccf86b017 - rustc_interface[94703aee012e7483]::passes::analysis
      40:     0x7f4ccfcea595 - <rustc_query_system[a1cbf340ec6d6f93]::dep_graph::graph::DepGraph<rustc_middle[c4bb946b42085c78]::dep_graph::dep_node::DepKind>>::with_task::<rustc_middle[c4bb946b42085c78]::ty::context::TyCtxt, (), core[c8091fc9dea0c6cf]::result::Result<(), rustc_errors[ae611370a546922c]::ErrorGuaranteed>>
      41:     0x7f4ccfd8f1fd - rustc_query_system[a1cbf340ec6d6f93]::query::plumbing::try_execute_query::<rustc_query_impl[f03dd36fb3d62396]::plumbing::QueryCtxt, rustc_query_system[a1cbf340ec6d6f93]::query::caches::DefaultCache<(), core[c8091fc9dea0c6cf]::result::Result<(), rustc_errors[ae611370a546922c]::ErrorGuaranteed>>>
      42:     0x7f4ccfdd58ee - rustc_query_system[a1cbf340ec6d6f93]::query::plumbing::get_query::<rustc_query_impl[f03dd36fb3d62396]::queries::analysis, rustc_query_impl[f03dd36fb3d62396]::plumbing::QueryCtxt>
      43:     0x7f4ccf8282a7 - <rustc_interface[94703aee012e7483]::passes::QueryContext>::enter::<rustc_driver[7b89ea061d8aedc7]::run_compiler::{closure#1}::{closure#2}::{closure#3}, core[c8091fc9dea0c6cf]::result::Result<(), rustc_errors[ae611370a546922c]::ErrorGuaranteed>>
      44:     0x7f4ccf81234f - <rustc_interface[94703aee012e7483]::interface::Compiler>::enter::<rustc_driver[7b89ea061d8aedc7]::run_compiler::{closure#1}::{closure#2}, core[c8091fc9dea0c6cf]::result::Result<core[c8091fc9dea0c6cf]::option::Option<rustc_interface[94703aee012e7483]::queries::Linker>, rustc_errors[ae611370a546922c]::ErrorGuaranteed>>
      45:     0x7f4ccf83bd3f - rustc_span[c774ced8c61a5d44]::with_source_map::<core[c8091fc9dea0c6cf]::result::Result<(), rustc_errors[ae611370a546922c]::ErrorGuaranteed>, rustc_interface[94703aee012e7483]::interface::create_compiler_and_run<core[c8091fc9dea0c6cf]::result::Result<(), rustc_errors[ae611370a546922c]::ErrorGuaranteed>, rustc_driver[7b89ea061d8aedc7]::run_compiler::{closure#1}>::{closure#1}>
      46:     0x7f4ccf8131e2 - <scoped_tls[a35f89285f520bf3]::ScopedKey<rustc_span[c774ced8c61a5d44]::SessionGlobals>>::set::<rustc_interface[94703aee012e7483]::interface::run_compiler<core[c8091fc9dea0c6cf]::result::Result<(), rustc_errors[ae611370a546922c]::ErrorGuaranteed>, rustc_driver[7b89ea061d8aedc7]::run_compiler::{closure#1}>::{closure#0}, core[c8091fc9dea0c6cf]::result::Result<(), rustc_errors[ae611370a546922c]::ErrorGuaranteed>>
      47:     0x7f4ccf82893f - std[f19dd7bb03296d5c]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[94703aee012e7483]::util::run_in_thread_pool_with_globals<rustc_interface[94703aee012e7483]::interface::run_compiler<core[c8091fc9dea0c6cf]::result::Result<(), rustc_errors[ae611370a546922c]::ErrorGuaranteed>, rustc_driver[7b89ea061d8aedc7]::run_compiler::{closure#1}>::{closure#0}, core[c8091fc9dea0c6cf]::result::Result<(), rustc_errors[ae611370a546922c]::ErrorGuaranteed>>::{closure#0}, core[c8091fc9dea0c6cf]::result::Result<(), rustc_errors[ae611370a546922c]::ErrorGuaranteed>>
      48:     0x7f4ccf828a99 - <<std[f19dd7bb03296d5c]::thread::Builder>::spawn_unchecked_<rustc_interface[94703aee012e7483]::util::run_in_thread_pool_with_globals<rustc_interface[94703aee012e7483]::interface::run_compiler<core[c8091fc9dea0c6cf]::result::Result<(), rustc_errors[ae611370a546922c]::ErrorGuaranteed>, rustc_driver[7b89ea061d8aedc7]::run_compiler::{closure#1}>::{closure#0}, core[c8091fc9dea0c6cf]::result::Result<(), rustc_errors[ae611370a546922c]::ErrorGuaranteed>>::{closure#0}, core[c8091fc9dea0c6cf]::result::Result<(), rustc_errors[ae611370a546922c]::ErrorGuaranteed>>::{closure#1} as core[c8091fc9dea0c6cf]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}

    error: internal compiler error: unexpected panic

    note: the compiler unexpectedly panicked. this is a bug.

    note: we would appreciate a bug report: https://github.com/rust-lang/rust/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md

    note: rustc 1.63.0-nightly (a6b8c6954 2022-06-03) running on x86_64-unknown-linux-gnu

    note: compiler flags: --crate-type bin -C embed-bitcode=no -C debuginfo=2 -C incremental

    note: some of the compiler flags provided by cargo are hidden

    query stack during panic:
    #0 [typeck] type-checking `main`
    #1 [typeck_item_bodies] type-checking all item bodies
    #2 [analysis] running analysis passes on this crate
    end of query stack