AudioService: move volume callback on AudioService

Robustness to crash of AudioServer.
Take benefit of future permission enforcement.

Bug: 293236285
Flag: EXEMPT refactor
Test: atest com.android.server.audio

Signed-off-by: Francois Gaffie <francois.gaffie@renault.com>
Change-Id: If556a668f45d608b98b6e8073426f5bb8128c7a2