drop logtostderr config option

This option has been removed in 1.26.

magnum/drivers/common/templates/kubernetes/fragments/configure-kubernetes-master.sh

@@ -64,9 +64,14 @@ fi
 KUBE_MASTER_URI="https://127.0.0.1:$KUBE_API_PORT"
 mkdir -p /srv/magnum/kubernetes/
 cat > /etc/kubernetes/config <<EOF
-KUBE_LOGTOSTDERR="--logtostderr=true"
 KUBE_LOG_LEVEL="--v=3"
 EOF
+# --logtostderr was removed in 1.26
+if [ "$kube_min_version" -le "25" ] ; then
+cat >> /etc/kubernetes/config <<EOF
+KUBE_LOGTOSTDERR="--logtostderr=true"
+EOF
+fi
 cat > /etc/kubernetes/kubelet <<EOF
 KUBELET_ARGS="--fail-swap-on=false"
 EOF