Remove/synchronize Torbutton SOCKS pref logic
In 4.5 (legacy/trac#14630 (moved)), we removed the Torbutton settings window because I assumed that users could use the Firefox proxy setting instead. Unfortunately, Torbutton still has code to check if its SOCKS settings match the browser proxy settings, and to disable itself if these are out of sync.
We should remove this old code so that it is easier for people to point TBB at a different Tor instance. The code is a toggle-era relic, and we have a control port check anyway.
We should also ensure that if the Tor check fails, Torbutton's features aren't actually disabled, and that the difference is only a cosmetic warning. Right now, I fear that features are actually disabled, due to other toggle-era checks.