Disable hip tests in CI

[lockshaw]

HIP tests currently all fail, and it's unlikely we'll have them passing in the near future (and they're currently not a priority for repo-refactor), so it would be good to temporarily disable them to reduce CI times.

[lockshaw]

Actually, there should really only be hip tests for utils and kernels as I think these are the only two libraries that actually use CUDA/HIP

[lockshaw]

Closed by #1083.