Cleanup nginx horizon sites by default

Horizon was moved under haproxy in Active/Active mode by default
This patch makes sures nginx sites are claened by default.

Change-Id: I2410eabf28391be21393241d266a01f82537cad5
Related-Prod: PROD-24978
Related-Prod: PROD-27224
diff --git a/nginx/server/proxy/openstack_web.yml b/nginx/server/proxy/openstack_web.yml
index 2de6606..db4453a 100644
--- a/nginx/server/proxy/openstack_web.yml
+++ b/nginx/server/proxy/openstack_web.yml
@@ -5,12 +5,14 @@
     nginx_proxy_openstack_web_buffer_size:
       number: 4
       size: 256
+    # starting from 2019.2.0 horizon is running under haproxy in HA mode.
+    nginx_server_site_nginx_proxy_openstack_web_enabled: False
   nginx:
     server:
       enabled: true
       site:
         nginx_proxy_openstack_web:
-          enabled: true
+          enabled: ${_param:nginx_server_site_nginx_proxy_openstack_web_enabled}
           type: nginx_proxy
           name: openstack_web
           proxy:
@@ -30,7 +32,7 @@
             protocol: ${_param:horizon_public_protocol}
           ssl: ${_param:nginx_proxy_ssl}
         nginx_ssl_redirect_openstack_web:
-          enabled: true
+          enabled: ${_param:nginx_server_site_nginx_proxy_openstack_web_enabled}
           type: nginx_redirect
           name: openstack_web_redirect
           host: