Release alarm wakelock if send fails

Now that we're acquiring a wakelock before we dispatch the alarm to the
app, we also need to release it in cases where the dispatch results in
an exception, because the only other release point is in the path of
alarm completion or timeout.

Test: atest FrameworksMockingServicesTests:AlarmManagerServiceTest

Flag: com.android.server.alarm.acquire_wakelock_before_send

Bug: 397950542
Change-Id: I7f119c51e2377841396efb360b38f51c1ab17915