Remove dead code related to legacy broadcast queue.

Bug: 266001401
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: I3382265ec033df159000ee993cb23f02668d5f67
8 files changed