Cleanup merge request refs of old closed/merged merge requests
In #223156 (closed), we worked on implementing a functionality to clean up merge request refs after 14 days an MR gets closed/merged.
As of this writing, it won't work for merge requests that were closed/merged prior to the change.
This issue is for adding a migration (likely a background migration) to apply the same thing for old merge requests (MRs that were closed/merged 14 or more days ago).
There's a worker and service that were added in !41555 (merged) that can be re-used if ever.
Edited by Patrick Bajao