Project mirroring or importing causes an enormous increase in git_garbage_collect jobs
9.3.1 introduced a change where changing project.import_status from started to finished results in housekeeping being performed. This in turn seems to have lead to GitLab.com ending up with 20 000 jobs in the git_garbage_collect queue, leading me to believe this is triggered every time we update a mirror since mirroring re-uses this state.
This is really problematic because it means updating a mirror will result in a job being scheduled. I looked at the queue and for many jobs housekeeping isn't even necessary.