ProjectExplorer: Fix crash on replaceSubtree

Do not double-free oldNode.

Change-Id: Icce2d13b6afd24f2e37c5ca7e2b572a6784e69e1
Reviewed-by: Orgad Shaneh <orgads@gmail.com>
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/projectexplorer/projectnodes.cpp

@@ -617,7 +617,6 @@ bool FolderNode::replaceSubtree(Node *oldNode, std::unique_ptr<Node> &&newNode)
         } else {
             takeNode(oldNode); // Happens e.g. when project is shutting down
         }
-        QTimer::singleShot(0, [oldNode]() { delete oldNode; });
     }
     handleSubTreeChanged(this);
     return true;