[Feature flag] Cleanup group_protected_branches

Summary

Related to Create and show protected branches (#372816 - closed)

This issue is to cleanup the group_protected_branches feature flag, after we cleaned up the allow_protected_branches_for_group feature flag. We only have the additional flag due to a naming conflict with a licensed feature. We kept it around in case anyone has manually enabled it so the feature didn’t suddenly disappear. Now that allow_protected_branches_for_group has been already cleaned up, we should remove group_protected_branches feature flag as well.

Owners

• Team: NAME_OF_TEAM
• Most appropriate slack channel to reach out to: #g_create_source-code-be
• Best individual to reach out to: @emmaspark
• PM: @mcbabin

Stakeholders

Expectations

What might happen if this goes wrong?

Not much, we're just cleaning up a flag

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 <feature-flag-name> 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 <feature-flag-name> --dev --pre --staging --staging-ref --production
• Close this rollout issue.