Fix QS expanding animation when there's scrolling

The bottom of QSContainerImpl has to be set to the bottom of the actual
view height. However, the bottom of the views that overlay the
background (and should pretend to be scrollable) should be corrected by
the interpolated scrolling range.

QS will draw behind the nav bar. This is only relevant when QS is long
(with media) and we are not using gesture nav. In that case, the bottom
padding/margin is enough that any buttons are still above the navbar.

Test: force scrolling and test manually
Change-Id: Ib0ffd1fe6824808fcf7a0774aa3523366cd869f9