We identified that the gin trigram index on notes (note)
can lead to very slow insert times on notes. It appears that
reindexing the index solves the problem. We have decided to
reindex it through migrations, first by creating a duplicate
index, then by dropping the old index.

Original MR thread: gitlab.com/gitlab-org/gitlab/-/issues/218410#note_565624409
Change MR: gitlab.com/gitlab-org/gitlab/-/merge_requests/61430