[GN] Hack around Dart 2 application_snapshot deps issue

For Dart 2 snapshots, application_snapshots() hardcodes a deps on
//utils/kernel-service:copy_kernel_service_snapshot

related #33167

Change-Id: I9a598e83a3e8ebb9a27bfe83132f3a957f2fea0e
Reviewed-on: https://dart-review.googlesource.com/56161
Reviewed-by: Nate Bosch <nbosch@google.com>
Commit-Queue: Zach Anderson <zra@google.com>

utils/dartanalyzer/BUILD.gn

@@ -21,9 +21,7 @@ analyzer_files = exec_script("../../tools/list_dart_files.py",
                              "list lines")
 
 application_snapshot("generate_dartanalyzer_snapshot") {
-  vm_args = [
-    "--preview-dart-2",
-  ]
+  dart_version = 2
   main_dart = "../../pkg/analyzer_cli/bin/analyzer.dart"
   training_args = [
     "--dart-sdk=" + rebase_path("../../sdk"),