yt-dlp flags spring cleaning

[vxbinaca]

• Annotations are dead and not used on Youtube, it's safe to remove this flag. No extractors use annotations.
• Delete call-home functionality to annoy about downloader updates from Youtube-dl days. We don't use that downloader anymore and that functionality isn't ideal and wasn't a good idea for me to put in.
• YT-DLP uses ffmpeg by default and avconv wasa dead project back in 2015

[brandongalbraith]

Hey @vxbinaca! Do you recall why you decided not to ship these changes? Asking only out of curiosity!

[vxbinaca]

Hey @vxbinaca! Do you recall why you decided not to ship these changes? Asking only out of curiosity!

I think it didn't work re: unit tests I don't even remember doing this.