Now that T211250 and T266717 are both finished, we can go ahead and delete everything from the mediawiki spicerack module that supports maintenance scripts implemented as cron jobs -- they're 100% systemd timers from now on. We ought to be able to get this done in time for the switch back to eqiad in September.
(Side note: I'm not sure if T266717 is intentionally still open, and if so whether it's because of this work in particular - @Legoktm feel free to rearrange the tasks in whatever way matches your intentions, including by closing this one as a dupe if that's what it is.)