Merge branch '515035-switch-member-role-and-admin-member-role' into 'master'

Switch member_role_type.rb and admin_member_role_type.rb inheritance

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/182341



Merged-by: Jarka Košanová <jarka@gitlab.com>
Approved-by: Jarka Košanová <jarka@gitlab.com>
Reviewed-by: Alex Buijs <abuijs@gitlab.com>
Co-authored-by: Daniel Tian <dtian@gitlab.com>