leaudio: Fix regression in unit test for codec_manager

Need to clear mock expectations.

Regression after
aa4d70f1 Move ConfigureDataPath out of AC

Bug: 310870184
Test: atest bluetooth_le_audio_codec_manager_test
Tag: #feature
Change-Id: I45abd2d2795f9a2d2ee4a9f614e8daa5529cc673