Disallow of selecting default value of media type fields for un-selected media types

Problem/Motivation

Disallow of selecting default value for un-selected media types

Steps to reproduce

1. Standard profile installation
2. Add media type field for the any available Content types
3. Choose "Image" in "Media type" of the "Reference type" setting (check screens above)
4. Click on "Set default value", then click "Add media" button. And you will see that we can actually choose media for all media types (audio, document, remote video, video and image). Moreover we can save everything and default value will be available on form display page, and on view display page !
5. It's very important to follow steps above in the same order, because if after 4th step (after save of field settings) we will go back to the field settings -> we can delete default media, then click again "Add media" and now we can select medias only for selected media types.