ConnDirectionStatistics is off by default, but most relays report it

Karsten noticed that most relays report ConnDirectionStatistics, but it's off by default in tor: https://lists.torproject.org/pipermail/tor-dev/2020-February/014159.html https://2019.www.torproject.org/docs/tor-manual.html.en

That's a bit of a mystery, here are some possible causes:

• most large distributions set it on by default
  • Debian + Ubuntu + ... ?
  • sample torrcs?
• there is a bug in most tor relays, that sets it on by default
  • since at least 0.2.9?

We don't have to fix this bug in Sponsor 55, but we need to be aware of it, because we're going to modify the ConnDirectionStatistics code.