music_album doesn't always need a from_activity_id

In the DB, music_album has a constraint (music_album_from_activity_id_b4915a61_fk_federation_activity_id) where they need a from_activity_id field. This makes no sense, not all albums are created by a federation activity, and accordingly when they are created this field is empty. However, one can't update an album without setting the field to something.