Elide intro_flutter_gpu (#2296)

For $REASONS, `intro_flutter_gpu` is breaking CI on the `master` branch.
Eliding from CI for the time being.

## Pre-launch Checklist

- [x] I read the [Effective Dart: Style] _recently_, and have followed
its advice.
- [x] I signed the [CLA].
- [x] I updated/added relevant documentation (doc comments with `///`).
- [x] All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-devrel
channel on [Discord].

<!-- Links -->
[Effective Dart: Style]:
https://dart.dev/guides/language/effective-dart/style
[CLA]: https://cla.developers.google.com/
[Discord]:
https://github.com/flutter/flutter/blob/master/docs/contributing/Chat.md

Author: domesticmouse

flutter_ci_script_master.sh

@@ -27,7 +27,8 @@ declare -a CODELABS=(
   "haiku_generator"
   "homescreen_codelab"
   "in_app_purchases"
-  "intro_flutter_gpu"
+  # TODO(domesticmouse): The protocol version of native_assets_cli-0.9.0 is 1.5.0, which is no longer supported.
+  # "intro_flutter_gpu"
   "namer"
   "next-gen-ui"
   "testing_codelab"