ProjectCacheWorker via `/api/v4/internal/post_receive` can result in 80k+ Gitaly calls
In certain circumstances, a single /api/v4/internal/post_receive
can lead to 80k n + 1 FindCommit
Gitaly calls onto the underlying repository from the Sidekiq ProjectCacheWorker
job.
This is also leading to the Gitaly Abuse detector alerting on possible abuse (it is not)
Example correlation_id
for which this occurs: https://log.gitlab.net/goto/23707633bf92f28f0068a74a32815a52
Example abuse report: https://gitlab.slack.com/archives/CCR9GMMR7/p1564577977042100