[4.0] Fix saving size in `CreateDialog`

Was fixed for 4.1 in godotengine/godot#75141, but as part of a larger
fix

editor/create_dialog.cpp

@@ -457,7 +457,7 @@ void CreateDialog::_notification(int p_what) {
 				search_box->call_deferred(SNAME("grab_focus")); // still not visible
 				search_box->select_all();
 			} else {
-				EditorSettings::get_singleton()->get_project_metadata("dialog_bounds", "create_new_node", Rect2(get_position(), get_size()));
+				EditorSettings::get_singleton()->set_project_metadata("dialog_bounds", "create_new_node", Rect2(get_position(), get_size()));
 			}
 		} break;