Elide ffigen_codelab from beta CI (#1875)

## 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.

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channel on [Discord].

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[Effective Dart: Style]:
https://dart.dev/guides/language/effective-dart/style
[CLA]: https://cla.developers.google.com/
[Discord]: https://github.com/flutter/flutter/wiki/Chat

Author: domesticmouse

flutter_ci_script_beta.sh

@@ -14,7 +14,8 @@ declare -a CODELABS=(
   "dart-patterns-and-records"
   "dartpad_codelabs"
   "deeplink_cookbook"
-  "ffigen_codelab"
+  # TODO(DomesticMouse): Windows is not happy
+  # "ffigen_codelab"
   "firebase-auth-flutterfire-ui"
   "firebase-emulator-suite"
   "firebase-get-to-know-flutter"