Switch everything to scheduled jobs

Everything that used the IdleMaintenance APIs/broadcasts gets to use the
spiffy new JobScheduler instead.  Hooray!

On top of that, the now-obsolete "idle maintenance" APIs are now gone
entirely.  Double hooray!

Bug 14993295

Change-Id: I5fb67c296ca8cd0ba8a2c8760a0f0d9d962d813b