Fix tv edu text drawer not closing completely

The edu text drawer closes by doing a slide animation - it looks like
it slides behind the pip content (even thought it is actually drawn on
top of the pip surface). We do the slide animation by having a
ValueAnimator animate from the current height of the drawer to 0. On
each animation update, we update the LayoutParams.height of the
TvPipEduTextDrawer until eventually the height converges to 0 and at
that point the edu text drawer is gone.

The pip menu surface size is updated on each frame of the animation.
To determine the necesary size for the pip menu surface, the
TvPipMenuController asks the TvPipMenuView to calculate that, taking
into account the current height of the edu text drawer. It does so by
using the View.getHeight() method. However, even though we set
LayoutParams.height to 0, the height of the edu text drawer remains 1,
which causes the pip menu surface to stay 1px bigger in height than
desired.

In this CL, we mitigate that by making the edu text GONE at the end of
the animation and returning 0 for the edu drawer height. This also
ensures a safe recovery in error states by making the final size of
the pip menu surface correct.

Bug: 275693800
Test: m SystemUI && verify white pip focus border touches the pip
      content without any grey line below the pip content
Change-Id: I4f3aec560ca7e2170e163852ce741fec349dfae4