Fix SSH sessions recorded on proxy not being fully closed

[gabrielcorado]

This issue affects only SSH sessions recorded at Proxy. When the session.Close is called from the Proxy, the session is not properly closed, leaving it open.

The problem was related to the session waiting for the parties to be closed (s.term.AddParty(-1)). This PR updates the close flow from session.Close and remoteTerminal.Close to fix it (commented on code).