Fix kube-router config generation (#5531)

Signed-off-by: Arthur Outhenin-Chalandre <arthur@cri.epita.fr>

roles/network_plugin/kube-router/templates/kubeconfig.yml.j2

@@ -0,0 +1,18 @@
+apiVersion: v1
+kind: Config
+clusterCIDR: {{ kube_pods_subnet }}
+clusters:
+- name: cluster
+  cluster:
+    certificate-authority: /var/run/secrets/kubernetes.io/serviceaccount/ca.crt
+    server: {{ kube_apiserver_endpoint }}
+users:
+- name: kube-router
+  user:
+    tokenFile: /var/run/secrets/kubernetes.io/serviceaccount/token
+contexts:
+- context:
+    cluster: cluster
+    user: kube-router
+  name: kube-router-context
+current-context: kube-router-context