Fix to not show mic input notification when communication device is other bluetooth device

Root Cause: We use getAvailableCommunicationDevices to show mic input notification, but did not
consider the case that other BT (car in this case) will coexist with hearing device.

Solution: Change to listen to the CommunicationDeviceChanged to show mic input notification when
communication device for now is hearing device.

Bug: 394070235
Test: atest HearingDevicePhoneCallNotificationControllerTest
Flag: com.android.server.accessibility.hearing_input_change_when_comm_device
Change-Id: I4ae002e407ee8f8e95dc6e22c49295585978067a