[le audio] Clear scan filters at scan stop

When scan is stopped, BASS should clear the filters so to avoid
duplicated filters and conflicts.

Bug: 395978182
Bug: 390317404
Flag: com.android.bluetooth.flags.leaudio_bass_scan_with_internal_scan_controller

Test: atest BassClientServiceTest
Test: manual test with broadcast scanning and confirm scan filter works
Change-Id: I6f7be0696955d3b163db0e0a90c8b89cbf3653f6