Fix rotation bounds calculation in WindowMagnificationControllerTest

On display WxH, a point (x,y) after 90 degree rotation is (y, W-x) in a
new coordinate.

Bug: 203361026
Test: atest com.android.systemui.accessibility.WindowMagnificationControllerTest#onOrientationChanged_enabled_updateDisplayRotationAndCenterStayAtSamePosition
Change-Id: I6fbe248873cd49a3ec52a56a060ade2620fe8710