Remove "-j KUBESERVICES" during teardown in 840 smoke test

Remove the rule to ensure that api-server is not accessible while
kube-proxy is not ready.

Otherwise, we have a race between "-j KUBE-FORWARD" and "-j WEAVE-NPC"
which makes the NodePort isolation test case to fail.

test/840_weave_kube_3_test.sh

@@ -5,6 +5,10 @@
 tear_down_kubeadm() {
     for host in $HOSTS; do
         run_on $host "sudo kubeadm reset && sudo rm -r -f /opt/cni/bin/*weave*"
+        # Remove the rule to ensure that api-server is not accessible while kube-proxy
+        # is not ready. Otherwise, we have a race between "-j KUBE-FORWARD" and "-j WEAVE-NPC"
+        # which makes the NodePort isolation test case to fail.
+        run_on $host "sudo iptables -t nat -D PREROUTING -m comment --comment \"kubernetes service portals\" -j KUBE-SERVICES" || true
     done
 }