smokescreen: Default to only listening on 127.0.0.1.

This prevents Smokescreen from acting as an open proxy.

Fixes #19214.

puppet/zulip/manifests/profile/smokescreen.pp

@@ -42,6 +42,7 @@ class zulip::profile::smokescreen {
     notify  => Service[supervisor],
   }
 
+  $listen_address = zulipconf('http_proxy', 'listen_address', '127.0.0.1')
   file { '/etc/supervisor/conf.d/zulip/smokescreen.conf':
     ensure  => file,
     require => [

puppet/zulip/templates/supervisor/smokescreen.conf.erb

@@ -1,5 +1,5 @@
 [program:smokescreen]
-command=/usr/local/bin/smokescreen-<%= @version %>
+command=/usr/local/bin/smokescreen-<%= @version %> --listen-ip <%= @listen_address %>
 priority=15
 autostart=true
 autorestart=true