Automatic merge from submit-queue

Change the name of the secret that delivers federation kubeconfig.

```release-note
Federation API server kubeconfig secret consumed by federation-controller-manager has a new name.

If you are upgrading your Cluster Federation components from v1.3.x, please run this command to migrate the federation-apiserver-secret to federation-apiserver-kubeconfig serect;

$ kubectl --namespace=federation get secret federation-apiserver-secret -o json | sed 's/federation-apiserver-secret/federation-apiserver-kubeconfig/g' | kubectl create -f -

You might also want to delete the old secret using this command:

$ kubectl delete secret --namespace=federation federation-apiserver-secret
```

The current name, federation-apiserver-secret, is very similar to the
other secret we have, federation-apiserver-secrets, that delivers
somewhat similar data but in a different format. This is extremely
confusing, particularly while debugging.

This change should soothe the pain.

cc @kubernetes/sig-cluster-federation