Cleanup launchd exporter

Also suppresses the deprecation warning for the launchd exporter when
using port instead of engine.port_for

lib/foreman/export/launchd.rb

@@ -7,6 +7,7 @@ class Foreman::Export::Launchd < Foreman::Export::Base
     super
     engine.each_process do |name, process|
       1.upto(engine.formation[name]) do |num|
+        port = engine.port_for(process, num)
         write_template "launchd/launchd.plist.erb", "#{app}-#{name}-#{num}.plist", binding
       end
     end