Stop crashing the system on hitting the alarm limit

Exempting the system as a runtime restart is not clearly
better than extreme memory and computation pressure that can result from
the originating spam.
Callers in the system should guard against any spammy requests that lead
them to create a lot of alarms.

Test: Builds, boots and existing tests should pass.

atest CtsAlarmManagerTestCases:UidCapTests
atest FrameworksMockingServicesTests:AlarmManagerServiceTest

Bug: 234441463
Bug: 210386776
Bug: 237230851
Change-Id: Id5e94d44ac9ab24870a8213ec7583da0f592a5ff