leaudio: unit tests for api:SetCodecConfigPreference

1. Add tests for setting preferred config to non active group
2. Add tests for setting single direction preferred cofig

Bug: 259191520
Bug: 353909820
Flag: TEST_ONLY
Test: atest bluetooth_le_audio_test bluetooth_le_audio_client_test
Change-Id: I40a016f236984857975f0f284cd3f82867ad55f5