GPUCP- 611 | Don't rely on mediawiki watchlist notification job

The redis part of this was being really weird, so I have deleted it. Instead, watchlist handling logic is somewhat copied from EmailNotification (ignoring enotif user options, however, since NotificationBroadcast handles that for us).

This has allowed the removal of setting the enotif settings in the preferences form save hook, preventing overwriting those settings on wikis which share properties storage with our own but do not enable Reverb.