QNX: Decrease number of objects created in tst_QJSEngine::newQObjectRace

This test is so slow on QNX that it times out:

QFATAL : tst_QJSEngine::newQObjectRace() Test function timed out
QObject: Cannot create children for a parent that is in a different thread.
(Parent is QGuiApplication(0x169b0a6b90),
parent's thread is QThread(0x37eb7070f0),
current thread is QThread(0x37eb734150)
FAIL!  : tst_QJSEngine::newQObjectRace() Received a fatal error.

Task-number: QTBUG-99168
Change-Id: I623bff212b8334af60198e52bc283cc97187c3a7
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

tests/auto/qml/qjsengine/tst_qjsengine.cpp

@@ -855,7 +855,11 @@ void tst_QJSEngine::newQObjectRace()
     {
         void run() override
         {
-            for (int i=0;i<1000;++i)
+            int newObjectCount = 1000;
+#if defined(Q_OS_QNX)
+            newObjectCount = 256;
+#endif
+            for (int i=0;i<newObjectCount;++i)
             {
                 QJSEngine e;
                 auto obj = e.newQObject(new QObject);