Add more tunnel ssh loggging (#18286)

Author: jeanp413

components/supervisor/pkg/supervisor/supervisor.go

@@ -1294,14 +1294,19 @@ func startAPIEndpoint(ctx context.Context, cfg *Config, wg *sync.WaitGroup, serv
 			return
 		}
 
+		log.Infof("tunnel ssh: Connected from %s", conn.RemoteAddr())
+
 		conn2, err := net.Dial("tcp", net.JoinHostPort("localhost", strconv.FormatInt(int64(cfg.SSHPort), 10)))
 		if err != nil {
 			log.WithError(err).Error("tunnel ssh: dial to ssh server failed")
 			return
 		}
 
 		go io.Copy(conn, conn2)
-		_, _ = io.Copy(conn2, conn)
+		_, err = io.Copy(conn2, conn)
+		if err != nil {
+			log.WithError(err).Error("tunnel ssh: error returned from io.copy")
+		}
 
 		conn.Close()
 		conn2.Close()