Remove “featured-instances”, since some of them including child porn content

Edvidence:

Instance: fedi.absturztau.be https://pedoblock.ignorelist.com/2020/12/31/instance-fedi-absturztau-be/

Instance: shitposter.club https://pedoblock.ignorelist.com/2021/01/15/instance-shitposter-club/

Honestly, I don't think it's a good idea that only adding a few of them in there, unfair to other instances want new users as well.