Fix rogue nested watcher triggering notifications registering too often

could potentially fix #1159 (closed) or at least speed it up a bit

requested review from @tusooa

I don't think this is relevant for mute words editing?

That watcher would be triggered on any settings change, and the re-registration handler that ends up being executed takes up like 300ms or worse. This makes all the other settings faster, which includes mute words.

merged

mentioned in commit eae62e2e