Stop ignoring should_refuse_unknown_exits() for unauthenticated channels

The brackets in this code are wrong in at least two ways:

• they unconditionally reject client channels
• there are two at the start

      if ((client_chan ||
           (!connection_or_digest_is_known_relay(
                or_circ->p_chan->identity_digest) &&
          should_refuse_unknown_exits(options)))) {

Bugfix on d52a1e2 in #22060 (moved), note that 66aff2d was merged into that code in 0.3.2.