Fix AccessibilityGestureDispatchTest failures

The getX()/getY() of motion evetns is based on the location
of the input window. However, the location of input window
is changed during window animation. It ends up the received
point doesn't match the expected value.

To fix it we need to wait for window animation completed.

Bug: 191382942
Test: atest AccessibilityGestureDispatchTest
Change-Id: Ib7934100bddb9b879134f4a45fd87b3b71d07720