Remove legacy code for retrieving Site To Site details

Earlier versions of Apache NiFi could potentially enter a distributed deadlock when load balancing with a Remote Process Group. Retrieval of these details was obtained within the framework as a remote call was technically unnecessary. Subsequently, these actions were made asynchronous but the port retrieval was left in place. This could lead to some confusion as the UI may report some ports as available when technically policies may prevent data transfers. By removing the legacy code, the UI will accurately reflect the port availability.