Hide ambient control when there's no valid control point

The preference will be accidentally shown if the device support HAP and
VCP. Make sure to hide the preference when the device doesn't have any
valid ambient control points.

Flag: EXEMPT bugfix
Test: manual test with real device
Test: atest BluetoothDetailsAmbientVolumePreferenceControllerTest
Bug: 388156028
Change-Id: I8162ce8e878baff414e4665c97aaf1c21aa51229