Merge branch 'backfill-root-storage-statistics-fork-sizes' into 'master'

Add Background Migration to Backfill Root Storage Statistics Fork Sizes

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/120916



Merged-by: Suraj Tripathi <stripathi@gitlab.com>
Approved-by: Suraj Tripathi <stripathi@gitlab.com>
Reviewed-by: Krasimir Angelov <kangelov@gitlab.com>
Reviewed-by: Vijay Hawoldar <vhawoldar@gitlab.com>
Co-authored-by: Jason Goodman <jgoodman@gitlab.com>