Updating tests for exact alarms

For apps targeting T, SCHEDULE_EXACT_ALARM will be denied by default.
Changing instrumentation to use USE_EXACT_ALARM, which cannot be
revoked.
Refactored some code in helper apps.

Test: atest CtsAlarmManagerTestCases

Bug: 226439802
BYPASS_INCLUSIVE_LANGUAGE_REASON=existing method names

Change-Id: I26cd0045010fb7e28d8dd715648f055910779403
19 files changed