Use buildjet cache instead of github cache on buildjet runners

[Voxelot]

Our customers frequently report issues with actions/cache, ranging from stalling downloads to slow performance. The issues don't only slow down workflow runs significantly, but can even negate the speed gains given by the faster BuildJet hardware when caches get large.
Despite our best efforts to address these issues, they remain unresolved. Coupled with the recent staff changes at GitHub's India team - responsible for maintaining actions/cache - the commit activity has halted and numerous performance and stability issues remain unresolved.

https://buildjet.com/for-github-actions/blog/launch-buildjet-cache#why-buildjet-cache

The rust cache action seems to take up a lot of time to download the cached artifacts in the sway CI. We should migrate to buildjet cache following the examples here:

- uses: buildjet/cache@v3
  with:
    path: |
      ~/.cargo/bin/
      ~/.cargo/registry/index/
      ~/.cargo/registry/cache/
      ~/.cargo/git/db/
      target/
    key: ${{ runner.os }}-cargo-${{ hashFiles('**/Cargo.lock') }}

https://buildjet.com/for-github-actions/docs/guides/migrating-to-buildjet-cache#rust

For comparison, on the fuel-core repo the cache takes mere seconds to run a full clippy pass:

Whereas on sway, the rust cache action took several minutes for the mdbook job: