VOL-1690: Use revision based compaction

Defaults to keeping 10 change revisions in etcd
Also use current 3.4.1 etcd

Change-Id: I458861a61c6a78ee0fc6f9579447eb13e597827a
diff --git a/voltha-etcd-cluster/templates/etcd-cluster.yaml b/voltha-etcd-cluster/templates/etcd-cluster.yaml
index 827ba0c..e41b67d 100644
--- a/voltha-etcd-cluster/templates/etcd-cluster.yaml
+++ b/voltha-etcd-cluster/templates/etcd-cluster.yaml
@@ -23,6 +23,8 @@
       limits:
         memory: {{ .Values.memoryLimit }}
     etcdEnv:
+    - name: ETCD_AUTO_COMPACTION_MODE
+      value: {{ quote .Values.autoCompactionMode }}
     - name: ETCD_AUTO_COMPACTION_RETENTION
       value: {{ quote .Values.autoCompactionRetention }}
     busyboxImage: {{ .Values.registry }}{{ .Values.images.busybox.repository }}:{{ tpl .Values.images.busybox.tag . }}