crimson/monc: drop misleading comment about Connection::reply.

crimson/monc: drop misleading comment about Connection::reply.

Before the commit the `crimson::mon:Connection::reply`
was commented as being specific to the ProtocolV1.
However, the code suggests this member participates also
in V2-related paths like `Connection::renew_tickets()`
where `do_auth()` is called from. `do_auth()` generates
`MAuth` which causes a monitor to send `MAuthReply`.
The `Connection::reply` synchronizes sending the auth
request with response handling.

Signed-off-by: Radoslaw Zarzynski <rzarzyns@redhat.com>