fe875083b3 confused things a bit and made
--no-subs-with-matching-audio actually mean what it says: no subtitles
if the languages match. However, the option actually meant no non-forced
subtitles not no subtitles at all. This isn't really intuitive so
instead of changing the behavior back to the old way (we already have a
release since then), add a third option "forced" which is equivalent to
the old meaning of --no-subs-with-matching audio. Fixes#13151.