Merge branch '492353-backfill-namespace-organization_id' into 'master'

Add migration for setting Namespace organization_id

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/170997



Merged-by: Tiger Watson <twatson@gitlab.com>
Approved-by: Bojan Marjanovic <bmarjanovic@gitlab.com>
Approved-by: Tiger Watson <twatson@gitlab.com>
Co-authored-by: Rutger Wessels <rwessels@gitlab.com>