KCC: simplify get_dsa_for_implied_replica(), using IP invariant

KCC: simplify get_dsa_for_implied_replica(), using IP invariant

We only do IP transports. Therfore the long list of alternatives...

                   (not n_rep.is_domain() or
                    n_rep.is_partial() or
                    cn_conn.transport_dnstr is None or
                    cn_conn.transport_dnstr.find("CN=IP") == 0)

that ends with the equivalant of "is this IP?" always evaluates to True.

If we leave it there it will confuse people for ever.

Signed-off-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Reviewed-by: Garming Sam <garming@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>