clientv3/integration: remove TestKVGetOneEndpointDown
clientv3/integration: remove TestKVGetOneEndpointDown

Already tested in other server shutdown tests.

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

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