Description of problem:
Creating clusterlogging, set ES `nodeCount: 1` and `redundancyPolicy: SingleRedundancy`, the clusterlogging could be created, and the ES pod could start. Check the logs in CLO and EO, no error message shows the redundancy policy is wrong. 

elasticsearch/elasticsearch:
    managementState: Managed
    nodeSpec:
      proxyResources:
        limits:
          memory: 64Mi
        requests:
          cpu: 100m
          memory: 64Mi
      resources:
        requests:
          memory: 2Gi
    nodes:
    - genUUID: 46fj9od5
      nodeCount: 1
      proxyResources: {}
      resources: {}
      roles:
      - client
      - data
      - master
      storage:
        size: 10Gi
        storageClassName: gp2
    redundancyPolicy: SingleRedundancy
  status:
    cluster:
      activePrimaryShards: 6
      activeShards: 6
      initializingShards: 0
      numDataNodes: 1
      numNodes: 1
      pendingTasks: 0
      relocatingShards: 0
      status: yellow
      unassignedShards: 4
    clusterHealth: ""
    conditions: []
    nodes:
    - deploymentName: elasticsearch-cdm-46fj9od5-1
      upgradeStatus: {}
    pods:
      client:
        failed: []
        notReady: []
        ready:
        - elasticsearch-cdm-46fj9od5-1-6f9f9556c8-vfnhs
      data:
        failed: []
        notReady: []
        ready:
        - elasticsearch-cdm-46fj9od5-1-6f9f9556c8-vfnhs
      master:
        failed: []
        notReady: []
        ready:
        - elasticsearch-cdm-46fj9od5-1-6f9f9556c8-vfnhs
    shardAllocationEnabled: all


Version-Release number of selected component (if applicable):
elasticsearch-operator.4.6.0-202008110953.p0 

How reproducible:
Always

Steps to Reproduce:
1. deploy CLO and EO
2. create clusterlogging CR instance, set logStore as below:
  logStore:
    type: "elasticsearch"
    retentionPolicy: 
      application:
        maxAge: 1d
      infra:
        maxAge: 3h
      audit:
        maxAge: 2w
    elasticsearch:
      nodeCount: 1
      redundancyPolicy: "SingleRedundancy"
      resources:
        requests:
          memory: "2Gi"
      storage:
        storageClassName: "gp2"
        size: "10Gi"
  visualization:
3. check the ES pod

Actual results:


Expected results:

In 4.5 and lower versions, when doing the same steps, the ES pod couldn't be deployed, and there has an error message in the elasticsearch: `Wrong RedundancyPolicy selected. Choose different RedundancyPolicy or add more nodes with data roles`.

Should have the same behavior in 4.6

Additional info: