MINOR: quic: remove unnecessary call to free_quic_conn_cids()

free_quic_conn_cids() was called in quic_build_post_handshake_frames()
if an error occured. However, the only error is an allocation failure of
the CID which does not required to call it.

This change is required for future refcount implementation. The CID lock
will be removed from the free_quic_conn_cids() and to the caller.

src/xprt_quic.c

@@ -2687,7 +2687,6 @@ static int quic_build_post_handshake_frames(struct quic_conn *qc)
     return 1;
 
  err:
-	free_quic_conn_cids(qc);
 	return 0;
 }