fix: separate docker-args outputs to avoid arg collisions

Emitting the restart policy as a `--restart` argument from a `docker-args-process-deploy` trigger exposed a latent gluing bug: proxy and builder triggers concatenated `$STDIN$output` with no separator, and the scheduler and builders appended `docker-args-process-*` output directly onto the older `docker-args-*` output, so adjacent arguments could merge into values like `--restart=on-failure:10--label`. A space is now inserted at both the trigger echo and the concatenation so arguments always stay separated.

plugins/traefik-vhosts/docker-args-process-deploy

@@ -166,7 +166,7 @@ trigger-traefik-vhosts-docker-args-process-deploy() {
     done <"$proxy_labels_file_path"
   fi
 
-  echo -n "$STDIN$output"
+  echo -n "$STDIN $output"
 }
 
 trigger-traefik-vhosts-docker-args-process-deploy "$@"