Flag Cleanup

Remove the following flags:
-telephony_thread_shred
-async_init_carrier_privileges_tracker
-ensure that the CarrierPrivilegesTracker unit tests run
 with the flags on and removed.

Fixes: 373979028
Fixes: 427850060
Flag: EXEMPT cleanup (non-functional change)
Test: atest FrameworksTelephonyTests

Change-Id: If9792740052153d2ee23cb5e783be2d6f4738b7c