Makefile: Use gcloud auth configure-docker instead of gcloud docker.
Makefile: Use gcloud auth configure-docker instead of gcloud docker.

coreos/etcd,coreos/etcd,gyuho/etcd,etcd-io/etcd,etcd-io/etcd,ajityagaty/etcd,rnaveiras/etcd,gyuho/etcd,rnaveiras/etcd,etcd-io/etcd,mkumatag/etcd,mqliang/etcd,rnaveiras/etcd,mkumatag/etcd,ajityagaty/etcd,mkumatag/etcd,mqliang/etcd,mqliang/etcd,ajityagaty/etcd