Migrate managed services from setting to policy xml

Change-Id: Ie20f91dbdd0ba6b57b5909cbf0152a32754fe02d
Fixes: 62263757
Test: runtest systemui-notification, cts AudioManagerTest,
cts-verifier DND tests, verify bug reports after toggling
access for various types of managed services, verified
default approved services aren't renabled on boot; verified that
they are reenabled after a device reset, verified that
settings are migrated after a restore from OC backup.