MINOR: checks: don't call conn_cond_update_polling() anymore

This was a leftover of the pre-mux v1.8-dev3 era. It makes no sense anymore
to try to disable polling on a connection we don't own, it's the mux's job
and it's properly done upon shutdowns and closes.

src/check.c

@@ -812,12 +812,6 @@ static int wake_srv_chk(struct conn_stream *cs)
 	else
 		HA_SPIN_UNLOCK(EMAIL_ALERTS_LOCK, &q->lock);
 
-	/* if a connection got replaced, we must absolutely prevent the connection
-	 * handler from touching its fd, and perform the FD polling updates ourselves
-	 */
-	if (ret < 0)
-		conn_cond_update_polling(conn);
-
 	return ret;
 }