Fix test fail for HearingDevicePhoneCallNotificationController

Root Cause: attempt to call addOnCommunicationDeviceChangedListeneron a previously registered listener, and fail on pts-bot:HFP/AG#HFP/AG/ECS/BV-03-I CtsTelecomTestCases CtsTelephonyTestCases

Solution: Add protection to not register it multiple times

Bug: 402755697
Bug: 402749422
Test: atest HearingDevicePhoneCallNotificationControllerTest
Test: atest pts-bot:HFP/AG#HFP/AG/ECS/BV-03-I CtsTelecomTestCases CtsTelephonyTestCases
Flag: com.android.server.accessibility.hearing_input_change_when_comm_device
Change-Id: I51dd57f5578b6672d91356273930371f088fcdd5