leaudio: set preferred codec config with context switch test part 1

scenario: idle(*) -> media -> conv -> media

Adding unit test for api:SetCodecConfigPreference for all use cases
during `*`

Bug: 259191520
Bug: 353909820
Flag: TEST_ONLY
Test: atest bluetooth_le_audio_test bluetooth_le_audio_client_test
Change-Id: Id3e7e1a4fa8566b4a013a00fe6116be9d28c585c