pdm: use disable_node on quantity_unit category

So that user can see the hierarchy (especially when categories are configured
s indented items) but not select nodes

bt5/erp5_pdm/SkinTemplateItem/portal_skins/erp5_pdm/Base_viewPDMFieldLibrary/my_quantity_unit_list.xml

@@ -10,8 +10,8 @@
             <key> <string>delegated_list</string> </key>
             <value>
               <list>
-                <string>title</string>
                 <string>items</string>
+                <string>title</string>
               </list>
             </value>
         </item>
@@ -71,6 +71,10 @@
                     <key> <string>target</string> </key>
                     <value> <string></string> </value>
                 </item>
+                <item>
+                    <key> <string>title</string> </key>
+                    <value> <string></string> </value>
+                </item>
               </dictionary>
             </value>
         </item>
@@ -86,6 +90,12 @@
                     <key> <string>form_id</string> </key>
                     <value> <string>Base_viewFieldLibrary</string> </value>
                 </item>
+                <item>
+                    <key> <string>items</string> </key>
+                    <value>
+                      <list/>
+                    </value>
+                </item>
                 <item>
                     <key> <string>target</string> </key>
                     <value> <string>Click to edit the target</string> </value>
@@ -108,7 +118,7 @@
       <dictionary>
         <item>
             <key> <string>_text</string> </key>
-            <value> <string>python: getattr(here.portal_categories[field.getId().replace(\'my_\', \'\', 1).replace(\'_list\', \'\')], preferences.getPreference(\'preferred_category_child_item_list_method_id\', \'getCategoryChildCompactLogicalPathItemList\'))(local_sort_id=(\'int_index\', \'translated_title\'), checked_permission=\'View\', filter_node=1)</string> </value>
+            <value> <string>python: getattr(here.portal_categories[field.getId().replace(\'my_\', \'\', 1).replace(\'_list\', \'\')], preferences.getPreference(\'preferred_category_child_item_list_method_id\', \'getCategoryChildCompactLogicalPathItemList\'))(local_sort_id=(\'int_index\', \'translated_title\'), checked_permission=\'View\', disable_node=True)</string> </value>
         </item>
       </dictionary>
     </pickle>