CI: test the `revive-llvm-builder` crate

Execute `make test-llvm-builder` but on a beefy machine. They take a long time to run so this job needs a deticated workflow that is only triggered if:
- Anything in `crates/llvm-builder` was changed
- Top level `Cargo.toml`, `Cargo.lock` or `LLVM.lock` was changed
- This workflow file itself was changed 