erp5_travel_expense: Fix rollback and use getIdOrUserName in workflow

bt5/erp5_travel_expense/WorkflowTemplateItem/portal_workflow/ticket_acceptance_simulation_workflow/variables/actor.xml

@@ -47,19 +47,13 @@
   </record>
   <record id="2" aka="AAAAAAAAAAI=">
     <pickle>
-      <tuple>
-        <tuple>
-          <string>Products.CMFCore.Expression</string>
-          <string>Expression</string>
-        </tuple>
-        <none/>
-      </tuple>
+      <global name="Expression" module="Products.CMFCore.Expression"/>
     </pickle>
     <pickle>
       <dictionary>
         <item>
             <key> <string>text</string> </key>
-            <value> <string>user/getUserName</string> </value>
+            <value> <string>user/getIdOrUserName</string> </value>
         </item>
       </dictionary>
     </pickle>