Fix: relayd close stream command was not working

Somehow, the stream last_net_seq_num was not updated on the relayd side
causing the close stream check to fail each single time.

However, the stream is also closed on a session destroy, if any, so
there is no leaks once the FD hung up and no broken feature.

Acked-by: Julien Desfossez <julien.desfossez@efficios.com>
Signed-off-by: David Goulet <dgoulet@efficios.com>