Merge branch 'refactor-user-assignments-resolver' into 'master'

Stop preloading policies for namespaces on self-managed instances

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/141774



Merged-by: Etienne Baqué <ebaque@gitlab.com>
Approved-by: Bishwa Hang Rai <bhrai@gitlab.com>
Approved-by: Etienne Baqué <ebaque@gitlab.com>
Reviewed-by: Etienne Baqué <ebaque@gitlab.com>
Reviewed-by: Bishwa Hang Rai <bhrai@gitlab.com>
Reviewed-by: Mohamed Hamda <mhamda@gitlab.com>
Co-authored-by: Mohamed Hamda <mhamda@gitlab.com>