Fix: Geometry Nodes: Leak of 4+ items of enum

There is extra one user of shared enum definition in case this is new one
so already exist user is enough. Also using of `new` operator to construct
enum definition make this impossible to catch such leask for trivial type.
`Vector` have 4-element inline buffer so this was trivial case for <=4 items.

Pull Request: https://projects.blender.org/blender/blender/pulls/117599

source/blender/blenkernel/intern/node_tree_update.cc

@@ -822,6 +822,8 @@ class NodeTreeMainUpdater {
           bNodeSocket &input = *node->input_sockets()[0];
           BLI_assert(input.is_available() && input.type == SOCK_MENU);
           this->set_enum_ptr(*input.default_value_typed<bNodeSocketValueMenu>(), enum_items);
+          /* Remove initial user. */
+          enum_items->remove_user_and_delete_if_last();
         }
         continue;
       }