[test] Fix slow async_catch_errors_test.

The default socket timeout is longer than the test timeout for some configurations.

Change-Id: Iddf60b6d40b8aa00115463fe76f1d924a93424bf
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/329640
Commit-Queue: Ryan Macnak <[email protected]>
Reviewed-by: Alexander Aprelev <[email protected]>

Author: rmacnak-google

tests/standalone/io/async_catch_errors_test.dart

@@ -13,7 +13,7 @@ var events = [];
 Future testSocketException() {
   var completer = new Completer();
   runZonedGuarded(() {
-    Socket.connect("4", 1).then((Socket s) {
+    Socket.connect("4", 1, timeout: Duration(seconds: 5)).then((Socket s) {
       Expect.fail("Socket should not be able to connect");
     });
   }, (err, s) {