Rollup merge of #135333 - vayunbiyani:test-environment, r=RalfJung

Partial progress on #132735: Replace extern "rust-intrinsic" with #[rustc_intrinsic] across the codebase

Part of #132735: Replace `extern "rust-intrinsic"` with `#[rustc_intrinsic]` macro

- Updated all instances of `extern "rust-intrinsic"` to use the `#[rustc_intrinsic]` macro.
- Skipped `.md` files and test files to avoid unnecessary changes.

Author: matthiaskrgr