Polish app open scrim animation.

We used to hide the scrim animation immediately, now we fade it out along with
the rest of the draglayer.

Also uses staggered workspace animation when resuming launcher from other
means ie. back gesture -> home

Bug: 145242991
Change-Id: Ib2161746f79ae5eaceac02d1416aa9bd7ecfeac4

src/com/android/launcher3/graphics/WorkspaceAndHotseatScrim.java

@@ -236,14 +236,6 @@ public class WorkspaceAndHotseatScrim extends Scrim {
         }
     }
 
-    public void hideSysUiScrim(boolean hideSysUiScrim) {
-        mHideSysUiScrim = hideSysUiScrim || (mTopScrim == null);
-        if (!hideSysUiScrim) {
-            mAnimateScrimOnNextDraw = true;
-        }
-        invalidate();
-    }
-
     private void setSysUiProgress(float progress) {
         if (progress != mSysUiProgress) {
             mSysUiProgress = progress;