AutoTest: Use new approach for settings

Avoids a couple of unneeded casts.

Change-Id: Ib3361d4ad2c69e4f0e4a44c5e9b3f385cefb6084
Reviewed-by: hjk <hjk@qt.io>

src/plugins/autotest/autotestunittests.cpp

@@ -77,10 +77,7 @@ void AutoTestUnitTests::initTestCase()
     }
 
     // Enable quick check for derived tests
-    static const Id id = Id("AutoTest.Framework.QtTest");
-    static_cast<Autotest::Internal::QtTestFramework *>(
-        TestFrameworkManager::frameworkForId(id))
-        ->quickCheckForDerivedTests.setValue(true);
+    theQtTestFramework().quickCheckForDerivedTests.setValue(true);
 }
 
 void AutoTestUnitTests::cleanupTestCase()