Don't allow core uids to be unfrozen due to deferrable broadcasts.

The special casing for core uids was added to ensure that we are not
adding the normal broadcast delay to these uids but if a process
belonging to a core uid is in a freezable state, we should defer all
the deferrable broadcasts.

Bug: 289397383
Test: atest services/tests/mockingservicestests/src/com/android/server/am/BroadcastQueueTest.java
Test: atest services/tests/mockingservicestests/src/com/android/server/am/BroadcastQueueModernImplTest.java
Change-Id: I47ce6ea68e2716a320198c008752cfaa7dedbb81