mrp: apply naming convention to my_view_mode_packing_list_listbox_variation_title

bt5/erp5_mrp/SkinTemplateItem/portal_skins/erp5_mrp/Base_viewMRPFieldLibrary/my_view_mode_packing_list_listbox_variation_title.xml

@@ -269,7 +269,7 @@
                 </item>
                 <item>
                     <key> <string>title</string> </key>
-                    <value> <string>listbox_variation_category_item_list</string> </value>
+                    <value> <string>Variation</string> </value>
                 </item>
                 <item>
                     <key> <string>unicode</string> </key>