Merge branch 'slashmanov/rapid-diffs-instrument-diffs-list-loading' into 'master'

Instrument Rapid Diffs list loading

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/183836



Merged-by: Phil Hughes <me@iamphill.com>
Approved-by: Thomas Randolph <trandolph@gitlab.com>
Approved-by: Phil Hughes <me@iamphill.com>
Co-authored-by: Stanislav Lashmanov <slashmanov@gitlab.com>