Merge branch '444222-finalize-namespace-id-backfill-on-notes' into 'master'

Finalize notes table sharding key backfill

See merge request !209336



Merged-by: Mario Celi <mcelicalderon@gitlab.com>
Approved-by: Adam Hegyi <ahegyi@gitlab.com>
Reviewed-by: GitLab Duo <gitlab-duo@gitlab.com>