Test: Fix PodCIDR issues on Kubernetes 1.7
Test: Fix PodCIDR issues on Kubernetes 1.7

On Kubernetes 1.7 PodSubnet was not correctly applied, because the
controller arguments had two times the parameters configured.

As seen in the code[0], if the PodSubnet is configured, all ExtraArgs
are created by Kubeadm.

[0] Kubernetes 1.7: https://github.com/kubernetes/kubernetes/blob/release-1.7/cmd/kubeadm/app/master/manifests.go#L450-L454
[0] Kubernetes master: https://github.com/kubernetes/kubernetes/blob/master/cmd/kubeadm/app/phases/controlplane/manifests.go#L304-L309

Fix #4338

Signed-off-by: Eloy Coto <2a8acc28452926ceac4d9db555411743254cf5f9@gmail.com>

michi-covalent/cilium,tklauser/cilium,tklauser/cilium,tgraf/cilium,scanf/cilium,scanf/cilium,tklauser/cilium,tgraf/cilium,michi-covalent/cilium,cilium-team/cilium,tklauser/cilium,tgraf/cilium,scanf/cilium,cilium-team/cilium,scanf/cilium,tgraf/cilium,tklauser/cilium,scanf/cilium,cilium/cilium,tgraf/cilium,eloycoto/cilium,eloycoto/cilium,michi-covalent/cilium,eloycoto/cilium,cilium/cilium,eloycoto/cilium,eloycoto/cilium,scanf/cilium,michi-covalent/cilium,scanf/cilium,cilium/cilium,michi-covalent/cilium,eloycoto/cilium,tgraf/cilium,cilium/cilium,eloycoto/cilium,cilium/cilium