erp5_wendelin_data_lake_ingestion: fix script to get logged in user

bt5/erp5_wendelin_data_lake_ingestion/SkinTemplateItem/portal_skins/erp5_wendelin_data_lake/ERP5Site_getUserName.py

 portal = context.getPortalObject()
-return portal.Base_getUserCaption()
+user_reference = portal.Base_getUserCaption()
+
+person = portal.portal_catalog.getResultValue(
+                portal_type = 'Person',
+                reference = user_reference)
+
+if person:
+  return '%s %s' % (person.getFirstName(), person.getLastName())
+else:
+  return user_reference