FIX: Keep parameter-less item labels aligned with foldout items [UUM-144325]

Hide the parameter-less header's expand arrow with visibility:Hidden instead
of display:None so the arrow retains its layout box and the label stays in the
same column as the labels of items that do have a foldout.

Author: Pauliusd01

Packages/com.unity.inputsystem/InputSystem/Editor/UITKAssetEditor/Views/NameAndParametersListView.cs

@@ -182,10 +182,11 @@ public NameAndParametersListViewItem(VisualElement root, ParameterListView param
             else
             {
                 // Hide the expand arrow and disable picking on the header toggle; the move/delete buttons are
-                // separate child elements and remain clickable.
+                // separate child elements and remain clickable. Use visibility (not display) so the arrow keeps
+                // its layout box and the header label stays aligned with the foldout items' labels.
                 var checkmark = header.Q(className: "unity-toggle__checkmark");
                 if (checkmark != null)
-                    checkmark.style.display = DisplayStyle.None;
+                    checkmark.style.visibility = Visibility.Hidden;
                 header.pickingMode = PickingMode.Ignore;
             }
         }