CppEditor: Fix running tests with clangd

Try harder to find a suitable kit:
  - Pick one without warnings.
  - Pick one with a Qt, as otherwise configureAsExampleProject()
    will fail.

Change-Id: I5a38e86bd81840c6794de365980618c904936d3a
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/cppeditor/followsymbol_switchmethoddecldef_test.cpp

@@ -494,8 +494,10 @@ void FollowSymbolTest::initTestCase()
         return;
 
     // Find suitable kit.
+    // Qt is not actually required for the tests, but we need it for consistency with
+    // configureAsExampleProject().
     F2TestCase::m_testKit = Utils::findOr(KitManager::kits(), nullptr, [](const Kit *k) {
-        return k->isValid();
+        return k->isValid() && !k->hasWarning() && k->value("QtSupport.QtInformation").isValid();
     });
     if (!F2TestCase::m_testKit)
         QSKIP("This test requires at least one kit to be present");