use the linked subtitles in the v4.3 api

some urls are without slug
also some video-Id's are shorter that 8 digits
and could probably be bigger than 8

some videos formats were not reported as DRM protected
fixes: yt-dlp#9652

new test file has no kill_date,
so I hope it will be online for longer
old one will be not available after "2024-08-12T21:05:00+02:00"

as display_id is optional it does not make sense to keep it

interrate over all subtitles and sort that `vtt` is default,
so `--embed-subs` is working out of the box

as `vtt_url` is the last in the list,
it will get priority

Co-authored-by: sepro <4618135+seproDev@users.noreply.github.com>