Expose multiple SQL backend usage validation error
Expose multiple SQL backend usage validation error

File-based domain-specific configuration supports only one SQL backend.
The method that checked how many SQL backends are enabled was not correct,
and depending on the order of domains examined, may give the wrong
result. A follow-on patch will fix this error.

Co-Authored-By: Henry Nash <henryn@linux.vnet.ibm.com>

Partial-Bug: #1410850
Change-Id: Idfc03ba5314acc7ebc8ed99f078b6a08130cc1dd

jumpstarter-io/keystone,nuxeh/keystone,klmitch/keystone,nuxeh/keystone,klmitch/keystone,mahak/keystone,roopali8/keystone,rajalokan/keystone,dims/keystone,ilay09/keystone,jonnary/keystone,cernops/keystone,jamielennox/keystone,roopali8/keystone,jumpstarter-io/keystone,vivekdhayaal/keystone,cernops/keystone,himanshu-setia/keystone,ilay09/keystone,takeshineshiro/keystone,rajalokan/keystone,dims/keystone,ilay09/keystone,ajayaa/keystone,openstack/keystone,rajalokan/keystone,openstack/keystone,nuxeh/keystone,mahak/keystone,takeshineshiro/keystone,vivekdhayaal/keystone,mahak/keystone,vivekdhayaal/keystone,openstack/keystone,maestro-hybrid-cloud/keystone,idjaw/keystone,dstanek/keystone,ajayaa/keystone,jamielennox/keystone,dstanek/keystone,maestro-hybrid-cloud/keystone,dstanek/keystone,jonnary/keystone,idjaw/keystone,himanshu-setia/keystone,jumpstarter-io/keystone