Remove BG service from calendar provider.

The purpose of EmptyService was to keep the process running until
it sends a broadcast with a delay which is scheduled with a handler...

However "sending a broadcast with a delay" can just be done

Bug 35350114

Test: Manual tests with the verbose log enabled.
- adb shell setprop log.tag.CalendarProvider2 VERBOSE &&
    adb shell am force-stop com.android.providers.calendar
- Then create/delete events on the calendar app and monitor
adb logcat | grep 'sendUpdateNotification'
- Then check the alarm and make sure PROVIDER_CHANGED is scheduled
at the right time.
adb shell dumpsys alarm | grep -A 4 -P 'ELAPSED.*com.android.providers.calendar'

Change-Id: Id2c0e10604bb7fdd3e9f8650295da83b3a62ecff
5 files changed