daemon/worker: decrease log level of uv_udp_connect() failure

In particular, ENETUNREACH happens on systems without IPv6,
and it doesn't make much sense to log about that by default:
  [io    ] Failed to establish udp connection: address not available

Introduced in 82e1d59 (v6.0.9).

Also log the IP address.

NEWS

@@ -1,3 +1,11 @@
+Knot Resolver 6.0.10 (202y-mm-dd)
+================================
+
+Improvements
+------------
+- avoid multiple log lines when IPv6 isn't available (!1633)
+
+
 Knot Resolver 6.0.9 (2024-11-11)
 ================================
 

daemon/worker.c

@@ -838,8 +838,10 @@ static int transmit(struct qr_task *task)
 		do {
 			ret = uv_udp_connect(udp, out_comm.comm_addr);
 		} while (ret == UV_EADDRINUSE && --connect_tries > 0);
-		if (ret < 0)
-			kr_log_error(IO, "Failed to establish udp connection: %s\n", uv_strerror(ret));
+		if (ret < 0) {
+			kr_log_info(IO, "Failed to establish udp connection to %s: %s\n",
+					kr_straddr(out_comm.comm_addr), uv_strerror(ret));
+		}
 	}
 	ret = qr_task_send(task, session, &out_comm, task->pktbuf);
 	if (ret) {