Warning about preferred bridge address lies

When the ClientUseIPv6 option was added (commit e04e1a2e) the logic for what a preferred OR port is changed. The warning about which OR port is prefered rewrite_node_address_for_bridge() now may say confusing things like "Will prefer IPv6 port" and then print an IPv4 port.

The address is correct. The address family, "IPv4" or "IPv6" may be wrong.