Cleanup labels.remove_on_close DB column

Since !62056 (merged) was reverted, we need to clean up this column because this was deployed / executed on some environments like GitLab.com

We need to follow the same steps in https://docs.gitlab.com/ee/development/avoiding_downtime_in_migrations.html#dropping-columns

1. Ignore the column (v14.0) - !62246 (merged)
2. Drop the column, check if column exists as it might not have been added in some envs/local installs as the migration is a no-op now (v14.1) - !62839 (merged)
3. Remove ignore column rule (v14.2) - !67367 (merged)