Lower media weight if catalognum exists

[MxMarx]

Beets doesn't seem to penalized the match distance if a release is missing a catalog number (as far as I can tell but I could easily be wrong).

If, for example, a release has a CD and digital version, and the digital one is missing the catalog number, then if media is removed from the query because the origin file has a catalog number, both media and catalog number might end up being ignored.