Ticket 47810 - investigate betxn plugins to ensure they
return the correct error code
Bug Description: Prior to backend transaction plugin types, postop error
codes didn't really have an effect, so often times a success
result was implicitly being returned.
Fix Description: Alawys return the correct error code for all backend transaction
plugins.
https://fedorahosted.org/389/ticket/47810
Jenkins: Passed
TET: Passed
Reviewed by: nhosoi(Thanks!)