Merge branch '429281-migrate-cr-instance' into 'master'

Migrate self-managed custom roles to the instance-level roles

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/147829



Merged-by: Adam Hegyi <ahegyi@gitlab.com>
Approved-by: Imre Farkas <ifarkas@gitlab.com>
Approved-by: Adam Hegyi <ahegyi@gitlab.com>
Co-authored-by: Jarka Košanová <jarka@gitlab.com>