Check context type with AUDIO_USAGE_VOICE_COMMUNICATION_SIGNALLING usage

As dial pad tone sound, the usage would be AUDIO_USAGE_VOICE_COMMUNICATION_SIGNALLING with context type unknown. When bt stack receive this usage metadata during media streaming, it would trigger the reconfiguration to conversational, because the conversational is higher priority than media in the general case. So we check context type with AUDIO_USAGE_VOICE_COMMUNICATION_SIGNALLING as well to avoid the unexpected reconfiguration

Bug: 231411704
Test: during media stream, and make the dial pad tone simultaneously, make
sure the media streaming normal

Change-Id: If14658e94282644d837bedff089e4029c7fc334c