session manager: change to null session on close

This fixes not assigning null to the websocket session id, which
prevented re logging in later due to login() reusing the closed sockets
id.

Fixes #8089

runelite-client/src/main/java/net/runelite/client/account/SessionManager.java

@@ -155,7 +155,7 @@ public class SessionManager
 
 	private void closeSession()
 	{
-		wsClient.close();
+		wsClient.changeSession(null);
 
 		if (accountSession == null)
 		{