Restores the opt-in default from before #60478. The schedule loop still runs in every server process and keeps its leader election; it only fires schedules in locations that enable the flag.
Co-authored-by: Dax <mail@thdxr.com>
Co-authored-by: Kit Langton <kit.langton@gmail.com>
Co-authored-by: James Long <longster@gmail.com>