Use renegotiations to update publisher connections with the HPB

When the HPB supports the "publisher-update" feature sending an updated
offer for a publisher will propagate the renegotiation to the
subscribers as well. Therefore, in those cases there is no need to force
a reconnection, it is enough to send the new offer to trigger the
renegotiation (given that all the clients will handle the updated offer
using the current connection).

Signed-off-by: Daniel Calviño Sánchez <danxuliu@gmail.com>