[Ambient Volume] Show value with remote data

Sync local data with remote data when UI need to refresh and set the
corresponding local value to remote when the control expanded/collapsed.

Flag: com.android.settingslib.flags.hearing_devices_ambient_volume_control
Bug: 357878944
Test: atest BluetoothDetailsAmbientVolumePreferenceControllerTest
Change-Id: If748e696eb62b199d4fd9abafa2300d301a8079c