Cleanup remove_legacy_github_client feature flag

Summary

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

Owners

• Team: ~"group::import"
• Most appropriate slack channel to reach out to: #g_manage_import
• Best individual to reach out to: @georgekoltsov
• PM: @hdelalic

Stakeholders

Expectations

What might happen if this goes wrong?

Cleaning up the feature flag

• Create a merge request to remove <feature-flag-name> feature flag. Ask for review and merge it. (!132544 (merged))
  • 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 9dc15245
• Close the feature issue to indicate the feature will be released in the current milestone.
• Clean up the feature flag from all environments by running these chatops command in #production channel:
  • /chatops run feature delete remove_legacy_github_client --dev
  • /chatops run feature delete remove_legacy_github_client --staging
  • /chatops run feature delete remove_legacy_github_client
• Close this rollout issue.