AutoTest: Use TestResult as value type

Don't construct it on heap and don't use shared pointer for it.

Change-Id: I51c9da405ed14d24b5f20242b4d049f9e2958f09
Reviewed-by: Christian Stenger <christian.stenger@qt.io>
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>

src/plugins/autotest/ctest/ctesttool.cpp

@@ -36,9 +36,7 @@ QString CTestTool::displayName() const
 
 ITestTreeItem *CTestTool::createRootNode()
 {
-    return new CTestTreeItem(this,
-                             displayName(),
-                             Utils::FilePath(), ITestTreeItem::Root);
+    return new CTestTreeItem(this, displayName(), {}, ITestTreeItem::Root);
 }
 
 } // namespace Internal