AutoTest: Use new test object setup

Change-Id: Icf750f084d8c2b5c34e62dfedd62bc785406d590
Reviewed-by: Christian Stenger <christian.stenger@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>

src/plugins/autotest/autotestplugin.h

@@ -51,9 +51,6 @@ public:
     static ChoicePair cachedChoiceFor(const QString &buildTargetKey);
     static void clearChoiceCache();
     static void popupResultsPane();
-
-private:
-    QVector<QObject *> createTestObjects() const override;
 };
 
 } // namespace Internal