leaudio: set preferred codec config with context switch test part 3

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: Ic4ffb1a9d8d97366e24e9d969e3fec9505504ea6