Merge branch 'jy-custom-roles-ff' into 'master'

Remove customizable_roles feature flag

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/114524



Merged-by: Allen Cook <acook@gitlab.com>
Approved-by: Allen Cook <acook@gitlab.com>
Approved-by: Gosia Ksionek <mksionek@gitlab.com>
Co-authored-by: Jessie Young <jessieyoung@gitlab.com>