[autotests] Try making KWinBindingsTest::testSwitchWindowScript more robust

Another random failure on build.kde.org (see T6546). This tries to use
QTRY_COMPARE on the SignalSpy's count instead of a wait in the hope that
this can handle the multi-threaded situation better. Though it might
also be possible that the other thread just didn't run in the 5 sec we
waited.

autotests/integration/kwinbindings_test.cpp

@@ -186,7 +186,7 @@ void KWinBindingsTest::testSwitchWindowScript()
         QSignalSpy runningChangedSpy(s, &AbstractScript::runningChanged);
         QVERIFY(runningChangedSpy.isValid());
         s->run();
-        QVERIFY(runningChangedSpy.wait());
+        QTRY_COMPARE(runningChangedSpy.count(), 1);
     };
 
     runScript(QStringLiteral("slotSwitchWindowUp"));