Replace openstack_proxy_address with cluster_public_host

In addition to template changes https://gerrit.mcp.mirantis.com/29621

Change-Id: I1d469d46e4931dec809c3f74ebbb3a98dfdc06a1
Closes-bug: PROD-24645 (PROD-25495)
diff --git a/nginx/server/proxy/openstack/horizon.yml b/nginx/server/proxy/openstack/horizon.yml
index a44f862..d35ffa2 100644
--- a/nginx/server/proxy/openstack/horizon.yml
+++ b/nginx/server/proxy/openstack/horizon.yml
@@ -2,7 +2,7 @@
   _param:
     nginx_proxy_openstack_api_host: ${_param:cluster_public_host}
     nginx_proxy_openstack_api_address: 0.0.0.0
-    nginx_proxy_openstack_horizon_host: ${_param:openstack_proxy_address}
+    nginx_proxy_openstack_horizon_host: ${_param:cluster_public_host}
   nginx:
     server:
       enabled: true