Fix Buck2 --out permission errors on macOS for claude code (#55736)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/55736

changelog: [internal]

On macOS with EdenFS backed directories, Buck2's --out flag fails with "Operation not permitted" error.

This fix works around the issue by:
1. Building to a temp directory outside the repo (os.tmpdir())
2. Removing extended attributes with `xattr -rc` on macOS

Reviewed By: cipolleschi

Differential Revision: D92078500

fbshipit-source-id: 437734c068e4bf20a4f8e570e1184565810154d3