Fix failure test cases in HearingAidDeviceManagerTest

We don't need to run the real AudioManager function, we just verify our own helper behavior.

Fix: 319755692
Test: make RunSettingsLibRoboTests ROBOTEST_FILTER=HearingAidDeviceManagerTest
Change-Id: Icfcccb658e532b4e16a4b7989ea911a442bd984c
1 file changed