Base_getWorkflowHistoryItemList: Remove access override

This script has no reason to be an exception to user's title retrieval
permissions.
Non-ERP5 users do not have applicable access control, so handle those
cases specifically. Such users may be:
- since-deleted ERP5 users
- coming from acl_users/zodb_users
Use a generic placeholder when the user is not allowed to see a
transition's actor.