Merge pull request #59836 from jpbetz/etcd-3.2.16-patch-upgrade

Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Bump etcd server patch version to 3.2.16

etcd 3.2.16 contains a critical fix for HA clusters: etcd-io/etcd#9281

Also, update newly added tests to use `REGISTRY` make variable.

Release note:
```release-note
Upgrade the default etcd server version to 3.2.16
```

Kubernetes-commit: 9aae9b58a5e2b78d27f2bd093fc1c4299bf63c36

artifacts/example/rc.yaml

@@ -21,4 +21,4 @@ spec:
         imagePullPolicy: Never
         command: [ "/kube-sample-apiserver", "--etcd-servers=http://localhost:2379" ]
       - name: etcd
-        image: quay.io/coreos/etcd:v3.2.14
+        image: quay.io/coreos/etcd:v3.2.16