Fix MediaCarouselController Tests

Enable tests and use real configuration object instead of a mock. Move
the check for the size media players and media content inside
reorderAllPlayers function because we only need to check when a new view
is actually added to media carousel.

Bug: 253229241
Test: atest MediaCarouselControllerTest
Change-Id: Ia8a7af53d02aa01b30941ada004a7da03603c821