Limit to deliver LOCKED_BOOT_COMPLETED before boot completed.

PackageManager can sometimes attempt to deliver LOCKED_BOOT_COMPLETED
to apps before boot process is complete, which can lead to a
system server crash.

Use the flag "FLAG_RECEIVER_REGISTERED_ONLY_BEFORE_BOOT" to
limit to deliver LOCKED_BOOT_COMPLETED before boot completed.

Flag: EXEMPT bugfix

Bug: 420361741
Test: atest BroadcastQueueImplTest
Test: atest BroadcastHelperTest
Change-Id: Ieb6a9d86a792a703f520a17366beeda679097083