fix(node): preserve AsyncLocalStorage context in unhandledRejection handlers (#32264)
## Summary
- Fixes `AsyncLocalStorage.getStore()` returning `undefined` inside
`unhandledRejection` / `unhandledrejection` event handlers
- Now matches Node.js behavior where the async context active at the
time of rejection is preserved
Fixes #30135
Actually fixed in https://github.com/denoland/deno/pull/32293, this just
adds a test.
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>