Disable as many timers as possible when DisableNetwork or when idle/hibernating
With #25373 (moved) and #25375 (moved), we should be using first-class timer objects for more and more of our timed events. We should have a way to mark timers that should be disabled when Tor is idle, or when DisableNetwork has been set. Then we should actually disable them, to lower the amount of wakeups that Tor performs under those circumstances.