Add missing lock to areAllUsersAffiliatedWithDeviceLocked

Added missing guards and @Guarded annotation by `getLockObject()`

Bug: 323495252
Change-Id: I49e835025940ee69138ee9782ef13e66fd7ee785
Test: Run CTS-Verifier "Check new user disclaimer" test and see a notification and a dialog are shown.
Flag: EXEMPT bugfix
1 file changed