Avoid "KeyError: material_name" crash in Fedora

Traceback (most recent call last):
      File "/usr/lib/python3.11/site-packages/UM/Qt/ListModel.py", line 54, in data
        return self._items[index.row()][self._role_names[role].decode("utf-8")]
               ~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    KeyError: 'material_name'

Downstream report: https://bugzilla.redhat.com/show_bug.cgi?id=2252195
Community: https://community.ultimaker.com/topic/44538-cura-53-crashs-at-startup/

For reasons unknown, this crash does not happen with the AppImage.

Nevertheless, in 2baada8a70
material_name was added as a role, not material_label.
Reaming the field in the sentinel extruder makes the crash go away.

cura/Machines/Models/ExtrudersModel.py

@@ -227,7 +227,7 @@ class ExtrudersModel(ListModel):
                     "material_brand": "",
                     "color_name": "",
                     "material_type": "",
-                    "material_label": ""
+                    "material_name": ""
                 }
                 items.append(item)
             if self._items != items: