🍒 screenedge: don't reduce approachGeometry
Reducing approachGeometry is not needed.
During edge creation, createHorizontalEdge and createVerticalEdge already substract the needed cornerOffset, and edges reserved by client windows shouldn't be reduced in geometry. In addition, during display, ScreenEdgeEffect confines the painted area to approachGeometry. So approachGeometry shouldn't be reduced in advance.
(cherry picked from commit 2f4db693)