CS-15175: Fix public interfaces of redundant router

We need to use ifup/ifdown to bring up the interfaces, because ifconfig don't
know the ip of the interface after we modify cloud-early-config to avoid
first start up of public interface.

Reviewed-by: Edison

patches/systemvm/debian/config/root/redundant_router/enable_pubip.sh.templ

@@ -5,8 +5,8 @@ set -e
 ip link|grep BROADCAST|grep -v eth0|grep -v eth1|cut -d ":" -f 2 > /tmp/iflist
 while read i
 do
-    ifconfig $i down
-    ifconfig $i up
+    ifdown $i
+    ifup $i
 done < /tmp/iflist
 ip route add default via [GATEWAY] dev eth2 && \
 service dnsmasq restart