Animate split divider

* TODO currently it doesn't animate when
dragging a split task back down because we need
to sync that with the other task scaling
animation playback controllers.
* It also doesn't animate in when opening a
split pair from overview because I think shell
is setting it to be visible before the divider
leash even makes it to launcher

Bug: 202914644

Change-Id: I6c60cffdb63aa262d0b547f85acc604c0c8a3637

quickstep/src/com/android/quickstep/views/RecentsView.java

@@ -4172,8 +4172,10 @@ public abstract class RecentsView<ACTIVITY_TYPE extends StatefulActivity<STATE_T
         mPendingAnimation.addEndListener(isSuccess -> {
             if (isSuccess) {
                 if (tv.getTaskIds()[1] != -1) {
+                    // TODO(b/194414938): make this part of the animations instead.
                     TaskViewUtils.setSplitAuxiliarySurfacesShown(mRemoteTargetHandles[0]
-                            .getTransformParams().getTargetSet().nonApps, true);
+                            .getTransformParams().getTargetSet().nonApps,
+                            true /*shown*/, false /*animate*/);
                 }
                 if (ENABLE_QUICKSTEP_LIVE_TILE.get() && tv.isRunningTask()) {
                     finishRecentsAnimation(false /* toRecents */, null);