[ CLI ] Fix incorrect string in smoke_test.dart

Change-Id: Ic60b0010d97b138c6afaa2d3606f4e41598fc41b
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/229120
Reviewed-by: Ben Konyi <bkonyi@google.com>
Commit-Queue: Ben Konyi <bkonyi@google.com>
diff --git a/pkg/dartdev/test/smoke/smoke_test.dart b/pkg/dartdev/test/smoke/smoke_test.dart
index 38dd049..671836d 100644
--- a/pkg/dartdev/test/smoke/smoke_test.dart
+++ b/pkg/dartdev/test/smoke/smoke_test.dart
@@ -63,7 +63,7 @@
         );
         expect(
           result.stderr,
-          'Could not start Observatory HTTP server: localhost:${server.port} is already in use.\n',
+          'Could not start VM service: localhost:${server.port} is already in use.\n',
         );
         expect(result.stdout, isEmpty);
         server.close();