[Flexiglass] disable carousel controller tests using legacy path.

Tests use media listeners should only run on non-flexi environment. This CL only disables the tests to run on flexi, we are not losing coverage as this new UI change will be implemented in the new remedia code.

Flag: com.android.systemui.scene_container
Fixes: 437954837
Test: atest MediaCarouselControllerTest
Change-Id: I1772313f1694c9f29a57c77249cfe0faf7a2a44d