Headset Client Profile AudioManager test

Headset Client tests were failing due to a null audioManager, this fixes
the test to get the correct mocked AudioManager.

Bug: 80261005
Test: runtest bluetooth -c com.android.bluetooth.hfpclient.HeadsetClientStateMachineTest
Change-Id: I547a33fc5f9555e91f5e1dadbab7b6543b047c11