AudioService: more LE audio/Hearing Aid volume fixes

Remove redundant LE Audio and Hearing Aid volume handling methods.
Align LE Audio and Hearing Aid volume updates when audio mode changes
and communication device is selected.
Do not perform volume initialization steps when a LE audio input device
is connected as those are needed only for an output device.

Bug: 349007365
Bug: 349244832
Test: make
Flag: EXEMPT bug fix
Change-Id: Ib9580515b8a9831cf4132525520c845204787eed