Remove comment complaining that we try to attach all streams to circs

It's inefficient, but the more efficient solution (only try to attach
streams aiming for this HS) would require far more complexity for a gain
that should be tiny.

src/or/rendclient.c

@@ -893,9 +893,6 @@ rend_client_receive_rendezvous(origin_circuit_t *circ, const uint8_t *request,
   onion_append_to_cpath(&circ->cpath, hop);
   circ->build_state->pending_final_cpath = NULL; /* prevent double-free */
 
-  /* XXXX023 This is a pretty brute-force approach. It'd be better to
-   * attach only the connections that are waiting on this circuit, rather
-   * than trying to attach them all. See comments bug 743. */
   circuit_try_attaching_streams(circ);
 
   memset(keys, 0, sizeof(keys));