Server interface state issues

[meyskens]

When running terraform plan after a successful create of online_server the plan wants to make the interface properties empty every time.

  ~ module.production_cluster.online_server.worker_server
      public_interface.address: "xxx.xxx.xxx.xxx" => ""
      public_interface.dns:     "rev.poneytelecom.eu." => ""
      public_interface.mac:     "xx:xx:xx:xx" => ""