protoproxy proxy_addresses is now optional

The protoproxy nginx configuration will always listen on the real server
IP which is required for LVS-DR.  On labs, the instance will only have
one real address so the proxy_addresses is not needed added since the
site already listen on the real server IP.

Change-Id: I8b44b269006be9cb43d2ba5ef4d2bc70d20149a8
Merge "protoproxy proxy_addresses is now optional" into production