Investigate intermittent gitserver CPU throttling

Created by: indradhanush

We recently doubled gitserver CPU on dotcom. While this has led to an overall reduction in CPU throttling to <1%, we still see occasional peaks of 15-20%. We should investigate what is causing this.

https://sourcegraph.com/-/debug/grafana/d/gitserver/git-server?viewPanel=100010&orgId=1&var-alert_level=All&var-shard=All&from=1635843223000&to=1636188823000

When the investigation is complete and a fix is rolled out, we should verify the fix and then proceed to merge #29317 after making necessary changes to the PR which will consequently fix #26925.