Allow bk cluster init to restart on failure (#303)

### Motivation

This is essentially the same as #176. Without this change, an init pod can fail and be in `Error` state even though the second pod succeeded. This will prevent misleading errors.

### Modifications

* Replace `Never` with `OnFailure`

### Verifying this change

This is a trivial change.

charts/pulsar/templates/bookkeeper-cluster-initialize.yaml

@@ -88,6 +88,6 @@ spec:
         {{- include "pulsar.toolset.certs.volumeMounts" . | nindent 8 }}
       volumes:
       {{- include "pulsar.toolset.certs.volumes" . | nindent 6 }}
-      restartPolicy: Never
+      restartPolicy: OnFailure
 {{- end }}
 {{- end }}