revert

revert 8e6ead1a as it change default behaviour

bt5/erp5_syncml/PropertySheetTemplateItem/portal_property_sheets/SyncMLSubscription/synchronization_id_generator_method_id_property.xml

@@ -53,7 +53,9 @@
         </item>
         <item>
             <key> <string>property_default</string> </key>
-            <value> <string>string:generateNewId</string> </value>
+            <value>
+              <none/>
+            </value>
         </item>
       </dictionary>
     </pickle>

bt5/erp5_syncml/bt/revision

-69
\ No newline at end of file
+70
\ No newline at end of file