tst_QGraphicsEffectSource: Reset effect repaint count after flushing events

Follow-up to 8222e06d12a4e2a84ce1161abd0ceb58622c740b, which only reset
the item repaint count.

Flushing the queued paint events will bump numRepaints, and the whole
point of calling reset() is to prepare a consistent state before the
next test, so we need to call it after flushing the events.

Pick-to: 6.2 6.4
Change-Id: Id1fe840c14c0940d7020cf8f8cc6a3aeceaa5fb5
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

tests/auto/widgets/graphicsview/qgraphicseffectsource/tst_qgraphicseffectsource.cpp

@@ -154,10 +154,10 @@ void tst_QGraphicsEffectSource::init()
     QVERIFY(effect);
     QVERIFY(item);
     QVERIFY(effect->source());
-    effect->reset();
     effect->storeDeviceDependentStuff = false;
     effect->doNothingInDraw = false;
     QCoreApplication::processEvents(); // Process all queued paint events
+    effect->reset();
     item->reset();
 }