Pinned stack animation: Also clear finalClipRect.

The code calculating it doesn't understand our scaling of Surface insets
and so it clips us too small. Since we scale to the stack bounds anyway
there is no sort of "draw over other apps" risk.

Bug: 35396882
Test: Move skeleton pip activity between states, ensure there are no cut off portions during animation.
Change-Id: I973db1879dd588d829e3fe828e9350f2647cdc2c

services/core/java/com/android/server/wm/WindowStateAnimator.java

@@ -1353,6 +1353,7 @@ class WindowStateAnimator {
             // expose the whole window in buffer space, and not risk extending
             // past where the system would have cropped us
             clipRect = null;
+            finalClipRect = null;
 
             // Various surfaces in the scaled stack may resize at different times.
             // We need to ensure for each surface, that we disable transformation matrix