Remove a workaround for an old SDK bug (#1271)

The linked issue is closed as fixed.
diff --git a/pkgs/test_api/lib/src/remote_listener.dart b/pkgs/test_api/lib/src/remote_listener.dart
index e745eb4..0bd44a2 100644
--- a/pkgs/test_api/lib/src/remote_listener.dart
+++ b/pkgs/test_api/lib/src/remote_listener.dart
@@ -61,10 +61,6 @@
       channel.sink.add({'type': 'print', 'line': line});
     });
 
-    // Work-around for https://github.com/dart-lang/sdk/issues/32556. Remove
-    // once fixed.
-    Stream.fromIterable([]).listen((_) {}).cancel();
-
     SuiteChannelManager().asCurrent(() {
       StackTraceFormatter().asCurrent(() {
         runZoned(() async {