Remove deprecated key from kubeadmconfig/v1beta4 (#11709)

timeoutForControlPlane has been removed from v1beta4, instead remplaced
by https://kubernetes.io/docs/reference/config-api/kubeadm-config.v1beta4/#kubeadm-k8s-io-v1beta4-Timeouts

The default for the new value are close enough that there is no need to
override them.

roles/kubernetes/control-plane/templates/kubeadm-config.v1beta4.yaml.j2

@@ -342,7 +342,6 @@ apiServer:
 {% for san in apiserver_sans %}
   - "{{ san }}"
 {% endfor %}
-  timeoutForControlPlane: 5m0s
 controllerManager:
   extraArgs:
   - name: node-monitor-grace-period