OLMIS-2812, make auth performance scenario be re-used
OLMIS-2812, make auth performance scenario be re-used

re-using this scenario in this way cuts down copy/pasted code, and is really only included here to be able to get a user token for the other requests.

OpenLMIS/openlmis-referencedata,OpenLMIS/openlmis-referencedata,OpenLMIS/openlmis-referencedata,OpenLMIS/openlmis-referencedata