Remove unnecessary Refresh() from wxGrid::OnDPIChanged()

The entire TLW is already refreshed when the DPI changes, so it's
unnecessary to refresh wxGrid window itself.

src/generic/grid.cpp

@@ -5413,8 +5413,6 @@ void wxGrid::OnDPIChanged(wxDPIChangedEvent& event)
 
     CalcDimensions();
 
-    Refresh();
-
     event.Skip();
 }