Fix the device on "Media devices" not updated issue

- This CL uses new CachedBluetoothDevice callback instance
  in construct to avoid unregister wrong callback.
- This CL uses flag to make sure preference will register callback
  on onAttached() when preference remove callback on
  onPrepareForRemoval() or onDetached().
- Update test case

Bug: 168682778
Bug: 157653997
Test: make -j42 RunSettingsRoboTests
Change-Id: I7a0d9f5332153ee80634e191847b84cd7c380b7d
Merged-In: I7a0d9f5332153ee80634e191847b84cd7c380b7d
(cherry picked from commit cafeab28)