Remove Sorbet typechecker

**What does this PR do?**:

This PR is spiritually a revert of #1607, when we added the Sorbet
typechecker to dd-trace-rb.

It includes two commits: One where we remove all configuration
and scaffolding surrounding Sorbet, and one where we remove all of the
`# typed: ...` magic comments and `include Kernel` definitions added
to make Sorbet happy.

**Motivation**:

As documented in #2641, the team has decided that the value vs pain
equation for Sorbet has shifted in the past months, and thus that
it was time to remove Sorbet.

**Additional Notes**:

Sorbet type checking in CI was actually removed earlier this week in
 #2617.

**How to test the change?**:

CI should still be green.

.gitattributes

@@ -1,2 +1 @@
 gemfiles/**/* linguist-generated=true
-sorbet/rbi/**/* linguist-generated=true

.github/labeler.yml

@@ -10,7 +10,7 @@ docs:
 
 # Only test changes
 dev/testing:
-  - all: [ '{spec/**,integration/**,benchmarks/**,sorbet/**}' ]
+  - all: [ '{spec/**,integration/**,benchmarks/**}' ]
 
 # Changes to Profiling
 profiling:

.gitignore

@@ -51,6 +51,3 @@ gemfiles/.bundle
 # Native extension binaries
 lib/*.bundle
 lib/*.so
-
-# Extra file kept by sorbet for debugging usage, as documented in https://sorbet.org/docs/adopting#step-6-source-control
-sorbet/rbi/hidden-definitions/errors.txt

Appraisals

@@ -25,8 +25,6 @@ REMOVED_GEMS = {
   :check => [
     'rbs',
     'steep',
-    'spoom',
-    'sorbet',
   ],
 }
 

Gemfile

@@ -112,17 +112,6 @@ if RUBY_PLATFORM != 'java'
 end
 
 group :check do
-  # For type checking
-  # Sorbet releases almost daily, with new checks introduced that can make a
-  # previously-passing codebase start failing. Thus, we need to lock to a specific
-  # version and bump it from time to time.
-  # Also, there's no support for windows
-  if RUBY_VERSION >= '2.4.0' && (RUBY_PLATFORM =~ /^x86_64-(darwin|linux)/)
-    gem 'sorbet', '= 0.5.10201'
-    gem 'spoom', '~> 1.1'
-  end
-
-  # type checking with steep
   if RUBY_VERSION >= '2.6.0' && RUBY_PLATFORM != 'java'
     gem 'rbs', '~> 2.8.1', require: false
     gem 'steep', '~> 1.3.0', require: false

Rakefile

@@ -467,36 +467,8 @@ Rake::ExtensionTask.new("ddtrace_profiling_loader.#{RUBY_VERSION}_#{RUBY_PLATFOR
   ext.ext_dir = 'ext/ddtrace_profiling_loader'
 end
 
-desc 'Runs the sorbet type checker on the codebase'
-task :typecheck do
-  if Gem::Version.new(RUBY_VERSION) < Gem::Version.new('2.3.0')
-    $stderr.puts 'Sorry, cannot run sorbet type checker on older rubies :(' # rubocop:disable Style/StderrPuts
-  else
-    begin
-      sh 'srb tc'
-    rescue
-      $stderr.puts( # rubocop:disable Style/StderrPuts
-        %(
-+------------------------------------------------------------------------------+
-|  **Hello there, fellow contributor who just triggered a Sorbet type error**  |
-|                                                                              |
-| We're still experimenting with Sorbet on this codebase. If possible, take a  |
-| stab at getting it to work, but feel free to unblock yourself by adding      |
-| a `# typed: false` or `# typed: ignore` comment at the top of files which    |
-| Sorbet is struggling with.                                                   |
-|                                                                              |
-| In particular, if you're adding a new integration, you'll need to use this   |
-| mechanism as Sorbet does not play well with optional dependencies.           |
-+------------------------------------------------------------------------------+
-)
-      )
-      raise
-    end
-  end
-end
-
-desc 'Runs rubocop + type check + main test suite'
-task default: ['rubocop', 'typecheck', 'spec:main']
+desc 'Runs rubocop + main test suite'
+task default: ['rubocop', 'spec:main']
 
 desc 'Runs the default task in parallel'
-multitask fastdefault: ['rubocop', 'typecheck', 'spec:main']
+multitask fastdefault: ['rubocop', 'spec:main']

docs/DevelopmentGuide.md

@@ -10,7 +10,6 @@ This guide covers some of the common how-tos and technical reference material fo
      - [Running tests](#running-tests)
      - [Checking code quality](#checking-code-quality)
      - [Running benchmarks](#running-benchmarks)
-     - [Type checking](#type-checking)
  - [Appendix](#appendix)
      - [Writing new integrations](#writing-new-integrations)
      - [Custom transport adapters](#custom-transport-adapters)
@@ -164,19 +163,6 @@ $ bundle exec appraisal ruby-3.0.4-contrib rake spec:benchmark
 
 Results are printed to STDOUT as well as written to the `./tmp/benchmark/` directory.
 
-## Type checking
-
-This library uses the [Sorbet](https://sorbet.org/) type checker. Sorbet can be run with `bundle exec srb tc` (or `bundle exec rake
-typecheck`). There's also Language Server Protocol support, if your editor supports it.
-
-Type checking can be controlled on a file-by-file manner, using a `# typed: ...` comment. The default (when none is provided) is assuming `# typed: false`.
-
-Things to note:
-
-* For compatibility with older Rubies, we use Sorbet but do not yet allow type annotations in the codebase. If Sorbet is blocking you, feel free to use `# typed: false` or `# typed: ignore` with a quick note on why this was needed. In many cases, Sorbet can typecheck a file correctly with no extra type annotations.
-
-* Most integration-specific code will reference optional external dependencies which Sorbet cannot see into. You'll probably need to use `# typed: false` or `# typed: ignore`  for those files as well.
-
 ## Appendix
 
 ### Writing new integrations