tst_QWindow::setVisibleThenCreate(): Fix unused argument warning

Use the arguments to call the parent class implementation.

Pick-to: 6.5 6.6
Change-Id: I602a66447fb8681b3ec9ef8e2e281828612d178c
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

tests/auto/gui/kernel/qwindow/tst_qwindow.cpp

@@ -254,7 +254,7 @@ public:
             if (type == QPlatformSurfaceEvent::SurfaceCreated)
                 ++surfaceCreatedEvents;
         }
-        return false;
+        return QWindow::eventFilter(o, e);
     }
 
     int surfaceCreatedEvents = 0;