Do not cancel quick settings expansion onQsIntercept(down)

ACTION_DOWN won't be followed by ACTION_MOVE for qs button tap so
- we should not assume DOWN is a qs expansion event
- we should not call #onQsExpansionStarted on DOWN, which cancels both
qs expansion and notifications animation downwards.

Fixes: 187685856
Test: swipe down from (top of lockscreen|open shade)
      tap qs button before qs expansion ends
      => qs expansion and notifications animation *not* frozen
         and complete running as expected

Change-Id: Ib4f3607b4b8bf9abaebcdf1bdaa09e45abe51297

packages/SystemUI/src/com/android/systemui/statusbar/phone/NotificationPanelViewController.java

@@ -1625,7 +1625,6 @@ public class NotificationPanelViewController extends PanelViewController {
                     mView.getParent().requestDisallowInterceptTouchEvent(true);
                 }
                 if (mQsExpansionAnimator != null) {
-                    onQsExpansionStarted();
                     mInitialHeightOnTouch = mQsExpansionHeight;
                     mQsTracking = true;
                     traceQsJank(true /* startTracing */, false /* wasCancelled */);