Make gitlab-org/gitlab build with Ruby 3

We need to add a CI build yaml that builds gitlab against Ruby 3.

Current test MR: !70798 (closed)

Remaining unit test failures to fix

• @alipniagov spec/factories_spec.rb
• @mkaeppler spec/models/user_spec.rb
  • ArgumentError: Cannot proxy frozen objects, rspec-mocks relies on proxies for method stubbing and expectations.
• @mkaeppler spec/lib/gitlab/instrumentation_helper_spec.rb
  • mem_* data not present -- is the memory patch not applied correctly?
  • Related failure: spec/initializers/lograge_spec.rb
• @alipniagov Stuck/slow jobs (time out):
  • https://gitlab.com/gitlab-org/gitlab/-/jobs/1481337643
  • https://gitlab.com/gitlab-org/gitlab/-/jobs/1481142931
• @mkaeppler spec/tooling/quality/test_level_spec.rb
  • Failure/Error: expect(subject.pattern(:system)).to be_frozen
• @mkaeppler More rspec table test failures
  • spec/models/integration_spec.rb
  • spec/models/project_spec.rb
• @mkaeppler Experiment engine kwargs error in lambda
  • spec/experiments/application_experiment_spec.rb
  • spec/experiments/new_project_readme_content_experiment_spec.rb
  • needs to be fixed in https://gitlab.com/gitlab-org/gitlab-experiment/-/blob/master/lib/gitlab/experiment/engine.rb#L38
  • add Ruby 3 build to this project?
• Seems also related to experiment ^ - @alipniagov
  • CycleAnalytics failure: https://gitlab.com/gitlab-org/gitlab/-/jobs/1493105836
  • create_service_spec failure: https://gitlab.com/gitlab-org/gitlab/-/jobs/1493105709
• @mkaeppler spec/lib/gitlab/fake_application_settings_spec.rb
• @alipniagov spec/lib/gitlab/import_export/attributes_permitter_spec.rb
  • kwargs error
• @mkaeppler ee/spec/lib/gitlab/ci/minutes/build_consumption_spec.rb
• @mkaeppler ee/spec/helpers/ee/user_callouts_helper_spec.rb
• @mkaeppler Multiple EE failures in https://gitlab.com/gitlab-org/gitlab/-/jobs/1480482090
• @mkaeppler ee/spec/models/license_spec.rb
• @alipniagov db:rollback geo argument error: https://gitlab.com/gitlab-org/gitlab/-/jobs/1493105924
• @mkaeppler RuboCop RedundantFreeze problem: https://gitlab.com/gitlab-org/gitlab/-/jobs/1493105650
• @mkaeppler More rspec table syntax specs:
  • https://gitlab.com/gitlab-org/gitlab/-/jobs/1493105685
  • https://gitlab.com/gitlab-org/gitlab/-/jobs/1493105920

integration spec failures

• grape exception in search_spec
  • filed issue upstream, using workaround for now