QmlDesigner: Remove "locked" auxiliary data instead of setting it false

Since absence of locked property implies it is not locked, simplify
the auxiliary data by just removing the locked property instead of
setting it to false.

Also remove unused private method ModelNode::removeLocked().

Task-number: QDS-2915
Change-Id: I27904514f168c28138b6311278f60565fc810f00
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>

src/plugins/qmldesigner/designercore/include/modelnode.h

@@ -248,7 +248,6 @@ public:
 private: // functions
     Internal::InternalNodePointer internalNode() const;
 
-    void removeLocked();
     bool hasLocked() const;
 
 private: // variables

src/plugins/qmldesigner/designercore/model/modelnode.cpp

@@ -1241,22 +1241,17 @@ bool ModelNode::hasLocked() const
 
 void ModelNode::setLocked(bool value)
 {
-    setAuxiliaryData(lockedProperty, value);
-
     if (value) {
+        setAuxiliaryData(lockedProperty, true);
         // Remove newly locked node and all its descendants from potential selection
         for (ModelNode node : allSubModelNodesAndThisNode()) {
             node.deselectNode();
             node.removeAuxiliaryData("timeline_expanded");
             node.removeAuxiliaryData("transition_expanded");
         }
-    }
-}
-
-void ModelNode::removeLocked()
-{
-    if (hasLocked())
+    } else {
         removeAuxiliaryData(lockedProperty);
+    }
 }
 
 bool ModelNode::isThisOrAncestorLocked(const ModelNode &node)