tst_qjsengine: Adjust to qtbase change

The _q_reregisterTimers private slot has been removed from Q_OBJECT in
b902b152af0bf144c9c9833502e1dcfae0166620, and consequently it will no
longer be picked up by engine.

Change-Id: I11f3636092dc66bffa0bc54c3f1dd8fcf36aa691
Reviewed-by: Ahmad Samir <a.samirh78@gmail.com>
Reviewed-by: Ville Voutilainen <ville.voutilainen@qt.io>

tests/auto/qml/qjsengine/tst_qjsengine.cpp

@@ -4654,7 +4654,6 @@ void tst_QJSEngine::privateMethods()
     }
 
     QVERIFY(privateMethods.contains("myPrivateMethod"));
-    QVERIFY(privateMethods.contains("_q_reregisterTimers"));
     privateMethods << QStringLiteral("deleteLater") << QStringLiteral("destroyed");
 
     QJSValueIterator it(jsWrapper);