Set seekbar listening when UMO is visible to user

CurrentlyExpanded is always true. So listening attribute in
seekbarViewModel is always true. This makes SystemUI execute a runnable
repeatedly.
A listener is added to MediaScrollViewHolder to update players seekbar
whenever visibleToUser attribute is updated to make sure that listening
attribute is false when UMO is not visible to user.

Bug: 268191023
Test: atest MediaCaroselControllerTest
Change-Id: I3296cd6b560fa886b2fdb1dc11634a4df746fde9