[CDM perm sync] End to end test fixes

1. Add signature verification
2. Commented unnecessary permission restore logic, which checks the
   permissions that can't be bypassed by the system uid.

Bug: 231474219

Test: manually tested end to end, and confirmed the permissions are
synced.

Change-Id: I582f318a8fe04d4120596be480760714b8e4acf1
5 files changed