Remove code to manage the exact alarm denylist

Now that exact alarms are denied to newer app installs for apps targeting T, the deny list is obsolete and the overhead of maintaining it is not worthwhile.

Test: atest CtsAlarmManagerTestCases
Test: atest FrameworksMockingServicesTests:com.android.server.alarm

Bug: 304846238
Change-Id: I4376e5ddbb2e470f3e3d690dd0866f4b470f455b