Adjustments for new media pipeline

This CL include small refactor to some methods. It also includes some
adjustments in loading media in new pipeline to match the old pipeline.

Flag: com.android.systemui.scene_container
Bug: 326408371
Test: atest SystemUiRoboTests:MediaFilterRepositoryTest
Test: atest SystemUiRoboTests:MediaCarouselInteractorTest
Change-Id: Iaa5024d4b4d7b7a65a7d253fa4577b3fecf5bf89