[HA Audio Output] Change category according to the audio definition

Root Cause: According to the audio definition, system sounds are UI touch sounds, unlock sounds, etc., so they are controlled by Media strategy.

Solution: Change Settings key that is not used yet from 'HEARING_AID_SYSTEM_SOUNDS_ROUTING' to HEARING_AID_NOTIFICATION_ROUTING'

Bug: 293251163
Test: atest SettingsProviderTest
Change-Id: Id29efca70361c61e6be48a479c16f0e10a798246
7 files changed