Add `needs-unwind` compiletest directive to `libtest-thread-limit` and replace some `Path` with `path` in `run-make`
Part of #121876 and the associated [Google Summer of Code project](https://blog.rust-lang.org/2024/05/01/gsoc-2024-selected-projects.html).
This PR does two things:
1. Add this to `libtest-thread-limit` ([Why?](https://github.com/rust-lang/rust/pull/128507#issuecomment-2315158014))
```
//@ needs-unwind
// Reason: this should be ignored in cg_clif (Cranelift) CI and anywhere
// else that uses panic=abort.
```
2. Use `path` instead of `Path` to simplify multiple run-make tests.
7dc2caba7b