Set etcd as the defualt external datastore from the controller while creating the UffizziCluster

like below
```
kind: UffizziCluster
apiVersion: uffizzi.com/v1alpha1
metadata:
  name: basic-etcd-x-8
spec:
  ingress:
    host: testns2.uclusters.app.qa-gke.uffizzi.com
  externalDatastore: etcd
```