Clear carrier privilege rules on SIM reset.

Synchronization blocks have been added for any reads of mCatService
and mCarrierPrivilegeRules since these are being nullified. There are
other thread-safety issues in this class which can be addressed in a
follow-up.

Includes other safe cleanup.

Bug: 33057511
Test: Switched carriers and verified rules were temporarily dropped
Change-Id: Id0fe6c9f5df025aa03b120968cd486e741c34ee9
Merged-In: Id0fe6c9f5df025aa03b120968cd486e741c34ee9