Migrate ejabberd UDP streams to openresty

And remove the other streams in the process, in favor of running haproxy
on all LBs.

nodes/draco.kosmos.org.json

@@ -45,6 +45,7 @@
       "kosmos_assets::nginx_site",
       "kosmos_discourse::nginx",
       "kosmos_drone::nginx",
+      "kosmos-ejabberd::nginx",
       "kosmos_garage::nginx_web",
       "kosmos_gitea::nginx",
       "kosmos_gitea::nginx_ssh",