Don't print that fallback isn't found in should_use_fallback()

The call can simply fail if it isn't found - which will be the case on
removeable install media.

Signed-off-by: Peter Jones <pjones@redhat.com>
Don't print things on the screen by default when everything works.

There's no point to this text, and it generally confuses people.

Signed-off-by: Peter Jones <pjones@redhat.com>