If URL cleanup for a URL has one or more required types, and one or more optional ones, the editing UI currently preselects the required types, but allows changing them to optional ones. This means the user can end up submitting a disallowed combination, and getting a not very clear error.

See the comments on MBS-13438 where Qobuz links preselect streaming and allow either that or streaming + download, but the user changed the preselected streaming to just download (a disallowed combination).

We should probably freeze mandatory options in the same way we do for cases where there's only one relationship type available, and just make the other possible types still available for selection when adding a second relationship for the URL.