LeAudio: Fix detecting gaming scenarios on microphone only devices

For a microphone-only devices, we need to look into the unresumed
playback session audio tracks to properly detect the gaming scenario.

Bug: 388499616
Test: atest bluetooth_le_audio_client_test
Flag: EXEMPT; regression tested with unit tests + dedicated test case added
Change-Id: Ia67792fd0055d41a6469a0c11df9d1f9ec4b215c