OffscreenEffect: Use drawWindow instead of renderWindow when rendering contents

renderWindow bypasses all other effects and simply calls the code that
is responsible for the final render of the window. This means that any
effects that are active on the window are skipped, including things that
may change how the window is rendered like the invert effect. To fix
that, ensure we render the window with all effects applied.

BUG: 459417

src/libkwineffects/kwinoffscreeneffect.cpp

@@ -113,7 +113,7 @@ void OffscreenData::maybeRender(EffectWindow *window)
         data.setProjectionMatrix(projectionMatrix);
 
         const int mask = Effect::PAINT_WINDOW_TRANSFORMED | Effect::PAINT_WINDOW_TRANSLUCENT;
-        effects->renderWindow(window, mask, infiniteRegion(), data);
+        effects->drawWindow(window, mask, infiniteRegion(), data);
 
         GLFramebuffer::popFramebuffer();
         m_isDirty = false;