[Feature Flag] Cleanup `locked_paths_mergeability_check`

Related to [Feature flag] Rollout of `locked_paths_mergeab... (#474705 - closed)

Summary

This issue is to cleanup the locked_paths_mergeability_check feature flag, after the feature flag has been enabled by default for an appropriate amount of time in production.

Owners

• Team: Create; Source Code
• Most appropriate slack channel to reach out to: #g_create_source_code_be
• Best individual to reach out to: @jwoodwardgl
• PM: @mcbabin

Stakeholders

Expectations

What might happen if this goes wrong?

1. Can't merge MRs which should be mergeable
2. Performance degradation on MR page
3. Redis saturation

Cleaning up the feature flag

• Specify in the issue description if this feature will be removed completely or will be productized as part of the Feature Flag cleanup
• Create a merge request to remove locked_paths_mergeability_check feature flag. Ask for review and merge it.
  • Remove all references to the feature flag from the codebase.
  • Remove the YAML definitions for the feature from the repository.
  • Create a changelog entry.
• Ensure that the cleanup MR has been deployed to both production and canary. If the merge request was deployed before the code cutoff, the feature can be officially announced in a release blog post.
  • /chatops run auto_deploy status <merge-commit-of-cleanup-mr>
• Close the feature issue to indicate the feature will be released in the current milestone.
• If not already done, clean up the feature flag from all environments by running these chatops command in #production channel: /chatops run feature delete locked_paths_mergeability_check --dev --pre --staging --staging-ref --production
• Close this rollout issue.