CI unstable test: test_leader_restart_validator_start_from_old_ledger

[jackcmay]

---- test_leader_restart_validator_start_from_old_ledger stdout ----
Error: JoinError(Any)
thread 'test_leader_restart_validator_start_from_old_ledger' panicked at 'assertion failed: (left == right)
left: 1,
right: 0', libtest/lib.rs:326:5
note: Some details are omitted, run with RUST_BACKTRACE=full for a verbose backtrace.
stack backtrace:
0: std::sys::unix::backtrace::tracing::imp::unwind_backtrace
at libstd/sys/unix/backtrace/tracing/gcc_s.rs:49
1: std::sys_common::backtrace::print
at libstd/sys_common/backtrace.rs:71
at libstd/sys_common/backtrace.rs:59
2: std::panicking::default_hook::{{closure}}
at libstd/panicking.rs:211
3: std::panicking::default_hook
at libstd/panicking.rs:221
4: std::panicking::rust_panic_with_hook
at libstd/panicking.rs:475
5: std::panicking::continue_panic_fmt
at libstd/panicking.rs:390
6: std::panicking::begin_panic_fmt
at libstd/panicking.rs:345
7: test::assert_test_result
at ./:8
8: multinode::__test::TESTS::{{closure}}
at tests/multinode.rs:509
9: core::ops::function::FnOnce::call_once
at /checkout/src/libcore/ops/function.rs:223
10: <F as alloc::boxed::FnBox>::call_box
at libtest/lib.rs:1451
at /checkout/src/libcore/ops/function.rs:223
at /checkout/src/liballoc/boxed.rs:642
11: __rust_maybe_catch_panic
at libpanic_unwind/lib.rs:105

[mvines]

Fixed by #2443