Reduce deprecation watcher frequency to 24h

This ES watcher currently runs on a 12h schedule. I originally did this so that regardless of your locale or timezone, you would be more likely to see these notifications during your working hours.

However, the problem with this is that due to our traffic distribution these reports now seesaw between "many" and "not so many" deprecation warning alerts, which sometimes gives the impression that we improved the outcome when instead we simply logged fewer deprecations due to lower traffic volumes.

Plus, the #backend channel isn't so active usually anyway so posting this only once a day should suffice for it to be visible enough.