clientv3/integration: add 'TestUserErrorAuth'
clientv3/integration: add 'TestUserErrorAuth'

Signed-off-by: Gyu-Ho Lee <3454051ee3341eb69bdf6fca40899cdad4d86496@gmail.com>

armstrongli/etcd,visheshnp/etcd,li-ang/etcd,xiang90/etcd,mqliang/etcd,akauppi/etcd,etcd-io/etcd,sebrandon1/etcd,ajityagaty/etcd,gyuho/etcd,YuleiXiao/etcd,sebrandon1/etcd,bdarnell/etcd,mkumatag/etcd,ajityagaty/etcd,etcd-io/etcd,mqliang/etcd,plasticbox/etcd,akauppi/etcd,coreos/etcd,mickep76/etcd,yudai/etcd,rnaveiras/etcd,visheshnp/etcd,vimalk78/etcd,vimalk78/etcd,gyuho/etcd,mickep76/etcd,cockroachdb/etcd,YuleiXiao/etcd,bdarnell/etcd,glevand/coreos--etcd,heyitsanthony/etcd,mkumatag/etcd,xiang90/etcd,dannysauer/etcd,glevand/coreos--etcd,mqliang/etcd,sinsharat/etcd,whuwxl/etcd,yudai/etcd,whuwxl/etcd,cockroachdb/etcd,joshix/etcd,joshix/etcd,rnaveiras/etcd,coreos/etcd,plasticbox/etcd,fanminshi/etcd,rnaveiras/etcd,mkumatag/etcd,heyitsanthony/etcd,a-robinson/etcd,dannysauer/etcd,bluebreezecf/etcd,fanminshi/etcd,sinsharat/etcd,ajityagaty/etcd,lorneli/etcd,bluebreezecf/etcd,armstrongli/etcd,li-ang/etcd,lorneli/etcd,a-robinson/etcd,etcd-io/etcd