Description of problem:
Update cluster.spec.kubernetesApiEndpoints.serverEndpoints.serverAddress to an invalid address, the federatedcluster status still is Ready


Version-Release number of selected component (if applicable):
$ oc get clusterversion
NAME      VERSION                             AVAILABLE   PROGRESSING   SINCE   STATUS
version   4.1.0-0.nightly-2019-05-09-204138   True        False         3h24m   Cluster version is 4.1.0-0.nightly-2019-05-09-204138

Federation v2 controller-manager version: version.Info{Version:"v0.0.8", GitCommit:"0d12bc3d438b61d9966c79a19f12b01d00d95aae", GitTreeState:"clean", BuildDate:"2019-04-11T04:57:35Z", GoVersion:"go1.11.2", Compiler:"gc", Platform:"linux/amd64"}



How reproducible:
Always

Steps to Reproduce:
1. Install federation v2 contfoller manager from operator hub
2. Join a cluster to federation
3. Check federatedcluster
$ oc get federatedcluster
NAME       READY
cluster1   True
4. Modify the cluster.spec.kubernetesApiEndpoints.serverEndpoints.serverAddress to an invalid address
$ oc get cluster cluster1 -ojson|jq .spec.kubernetesApiEndpoints.serverEndpoints[].serverAddress
"https://test.invalid.com"
5. Check federatedcluster


Actual results:
After 10 minutes
$ oc get federatedcluster
NAME       READY
cluster1   True


Expected results:
Cluster1 status changes to "Offline"

Additional info:
If restart controller manager, federatedcluster status can be changed.
$ oc get federatedcluster
NAME       READY
cluster1   

$ oc get federatedcluster cluster1 -ojson|jq .status
{
  "conditions": [
    {
      "lastProbeTime": "2019-05-14T06:36:54Z",
      "lastTransitionTime": "2019-05-14T06:36:13Z",
      "message": "cluster is not reachable",
      "reason": "ClusterNotReachable",
      "status": "True",
      "type": "Offline"
    }
  ]
}