remove outdated tor relay security recommendations and update these wiki pages

While working on #24497 (moved) I wanted to link to existing security related recommendations and found:

https://trac.torproject.org/projects/tor/wiki/doc/TorRelaySecurity https://trac.torproject.org/projects/tor/wiki/doc/OperationalSecurity

IMHO these are severely outdated and give bad advises.

I'm proposing to remove some outdated content and if no one disagrees I'll proceed soon. I'll send email to tor-dev about this.