leaudio: set preferred codec config media test part 1

Adding unit tests for api:SetCodecConfigPreference for all use cases
before starting media streaming.

Bug: 259191520
Bug: 353909820
Flag: TEST_ONLY
Test: atest bluetooth_le_audio_test bluetooth_le_audio_client_test
Change-Id: I377e2a6588a388ecf3db3df375985cbd5af75d6a