RPKI: Remove port (and SSH username) from 'Cache server' output line

RPKI: Remove port (and SSH username) from 'Cache server' output line

It was mixed-up if hostname is IPv6 address, and reporting separate
values (like port) on separate lines fits better into key-value style
of 'show protocols all' output. Also, the patch simplifies transport
identification formatting (although it is unused now).

Thanks to Alarig Le Lay for the suggestion.