Un-hardcoding horizon address in nginx

The patch un-hardcodes horizon address in nginx site to be
used for redirection from 443 port to 8078.

Change-Id: Icec7a0534d6e9e8026ad5653b3cb9ab4004cf9fa
Related-PROD: PROD-25528
diff --git a/nginx/server/proxy/openstack_web.yml b/nginx/server/proxy/openstack_web.yml
index a9a4894..2de6606 100644
--- a/nginx/server/proxy/openstack_web.yml
+++ b/nginx/server/proxy/openstack_web.yml
@@ -14,7 +14,7 @@
           type: nginx_proxy
           name: openstack_web
           proxy:
-            host: localhost
+            host: ${_param:horizon_server_bind_address}
             # TODO: port must be configurable, as some deployments might have HAproxy over prx nodes
             port: 8078
             size: 10000m