In the stopping/shutdown state return unlock state of the user key

UserManager.isUserUnlocked should return true when user is stopping,
but encryption key is unlocked. Otherwise it causes issues in
non-cryptoaware apps that can can run while user is in STATE_STOPPING

Test: create/start/remove managed profiles in a loop and verify there
      are no app or system crashes
Bug: 38212686

Change-Id: I47aa520269aafe3d3c967b6841ff46e765c446bd