clientv3: test health balancer gray listing
clientv3: test health balancer gray listing

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