Branch deletion timing out

Manual branch deletion of projects in gitlab-org/gitlab was timing out.

Here is a screenshot from one of the reports:

I was also able to replicate the problem by trying to manually delete one of my ~5 month old branches.

I also suspect that branch-deletion-after-merge might have been timing out as well.

I also believe this problem correlates with having pre-receive secret detection enabled. We enabled it at ~17:08UTC and disabled it at ~23:25UTC.

cc @amarpatel @smeadzinger