remove_column should only be used in the up (or change) step of a migration if
it's a post-deployment migration. Otherwise there will be downtime due to the
ActiveRecord column cache, which we can avoid by using the IgnorableColumn
concern in combination with a post-deployment migration.
This is really weird. I think we did get the same issue while
migrating on GitLab.com. We fixed this by adding job_id to
ci_builds table manually, and then run the migrations again.
However I think we didn't hit into this on staging, which should
somehow be a production clone.
At any rate, I guess we could check if the column exists in the
migration. If the column is not there, there's no point to remove
that column anyway.
Closes#29976
Jan Provaznik