Removing legacy alarm batching algorithm

The current method of batching has shown reduced number of batches and
has been turned on for a while now. It is now time to bid farewell to
the old batching algorithm that has served us well for multiple
releases.

Test: Builds and boots normally.
Test: atest FrameworksMockingServicesTests:com.android.server.alarm
Test: atest CtsAlarmManagerTestCases

Bug: 228652215
Change-Id: Ic1f16c74b1f8b9191910cbb25c357dc9985fb240