leaudio: set preferred codec config with context switch test part 2

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: I06db70cce4c129ed57bd4352d948aa4bb13fcdf0