Remove failing mirrors

[traumschule]

Working on #22182 the updated script reported several issues with currently listed mirrors. They should be removed (by running the script with --remove-failing) if the errors turn out to be permanent.

Instructions for configuring a mirror:
​https://www.torproject.org/docs/running-a-mirror.html.en

[traumschule]

The script listed following issues. Currently 43 mirrors are up.

Connection timed out:
        http://btn6gqzqevlhoryd.onion/project/trace/www-master.torproject.org
        http://hbpvnydyyjbmhx6b.onion/mirrors/torproject.org/project/trace/www-master.torproject.org                                                                                                  
        http://torprowdd64ytmyk.onion/project/trace/www-master.torproject.org
        http://tmdrhl4e4anhsjc5.onion/project/trace/www-master.torproject.org
        http://44.225.40.254/torproject.org/dist/project/trace/www-master.torproject.org
        http://oldsqlcbr3aykyta.onion/tor/project/trace/www-master.torproject.org

hostname verification failed:
        https://108.248.87.242/project/trace/www-master.torproject.org
        https://108.248.87.242/dist/torbrowser/8.0.2/sha256sums-signed-build.txt
        https://tor.ozgurlesin.org/project/trace/www-master.torproject.org
        https://tor.ozgurlesin.org/dist/torbrowser/8.0.2/sha256sums-signed-build.txt

(The errors come right from ​LWP, error handling might be easier with ​Mojo though).

[traumschule]

The current version can be seen at ​https://github.com/torproject/webwml/pull/58

[traumschule]

Mail to the mirrors list has been sent:
​https://lists.torproject.org/pipermail/tor-mirrors/2018-October/001173.html