Use ELAPSE_REALTIME alarm for tick event

Change to use a real item alarm for scheduling ACTION_TIME_TICK
intents for the case where time goes backwards after the tick intent
is schedule, and where the time change is not noticed from the call
to waitForAlarm().

Bug: 5166877
Change-Id: I46b9a1c80146d27becedc341c4af977fcdf47352