msg/async: do not register lossy client connections

msg/async: do not register lossy client connections

If our policy is server + lossy, we do not need to track our incoming
client connections by address.  First, because it doesn't do us any good.
Second, it is nicer if we don't, because we can allow multiple incoming
connections from the same peer addr.

Update a couple of tests: one doesn't apply any more, and the other needs
a different way of getting the just-accepted con ref.

Signed-off-by: Sage Weil <sage@redhat.com>