kamailio.cfg: use xalert instead of old format for xlog, similar as done in other cfg places

etc/kamailio.cfg

@@ -626,7 +626,7 @@ route[REQINIT] {
 			exit;
 		}
 		if (!pike_check_req()) {
-			xlog("L_ALERT", "ALERT: pike blocking $rm from $fu (IP:$si:$sp)\n");
+			xalert("ALERT: pike blocking $rm from $fu (IP:$si:$sp)\n");
 			$sht(ipban=>$si) = 1;
 			exit;
 		}