don't scale highlighted window in present windows during de/activation

BUG: 283481
it's even worse, since it interferes with generally upscaled windows
(keeps them big, applies false transition and causes a final snapback)
and windata->highlight doesn't end at zero, so the entire screen is
still a little scaled when the effect ends (and snaps down afterwards)

now it snaps down when starting the leave what is better in general
and the only usable solution for upscaled windows.
some day presentwindows might be derived from the yet-to-add
animationeffect class ;-)

effects/presentwindows/presentwindows.cpp

@@ -348,7 +348,7 @@ void PresentWindowsEffect::paintWindow(EffectWindow *w, int mask, QRegion region
             m_motionManager.apply(w, data);
             QRect rect = m_motionManager.transformedGeometry(w).toRect();
 
-            if (winData->highlight > 0.0) {
+            if (m_activated && winData->highlight > 0.0) {
                 // scale the window (interpolated by the highlight level) to at least 105% or to cover 1/16 of the screen size - yet keep it in screen bounds
                 QRect area = effects->clientArea(FullScreenArea, w);
                 QSizeF effSize(w->width()*data.xScale, w->height()*data.yScale);