ci: Refine Rust test suite for CUDA support

- Removed 'test-opencl' job from the Rust workflow file (.github/workflows/rust.yml).
- Rust test suite is no longer being tested with OpenCL enabled, but continues to be tested with CUDA enabled through the 'test-cuda' job.

.github/workflows/rust.yml

@@ -113,43 +113,3 @@ jobs:
       - name: CUDA tests
         run: |
           cargo nextest run --release --no-default-features --features cuda,pasta,bls,arity2,arity4,arity8,arity11,arity16,arity24,arity36
-
-    # Runs the test suite on a self-hosted GPU machine with CUDA and OpenCL enabled (that is using the OpenCL backend for NVIDIA GPUs)
-  test-opencl:
-    name: Rust tests on OpenCL
-    runs-on: self-hosted
-    env:
-      NVIDIA_VISIBLE_DEVICES: all
-      NVIDIA_DRIVER_CAPABILITITES: compute,utility
-      EC_GPU_FRAMEWORK: opencl
-    steps:
-      - uses: actions/checkout@v4
-        with:
-          repository: lurk-lab/ci-workflows
-      - uses: ./.github/actions/ci-env
-      - uses: actions/checkout@v4
-      - uses: dtolnay/rust-toolchain@stable
-      - uses: taiki-e/install-action@nextest
-      - uses: Swatinem/rust-cache@v2
-      - name: Install GPU deps
-        run: |
-          apt-get update
-          apt-get -y install ocl-icd-opencl-dev
-      # Check we have access to the machine's Nvidia drivers
-      - run: nvidia-smi
-      # The `compute`/`sm` number corresponds to the Nvidia GPU architecture
-      # In this case, the self-hosted machine uses the Ampere architecture, but we want this to be configurable
-      # See https://arnon.dk/matching-sm-architectures-arch-and-gencode-for-various-nvidia-cards/
-      - name: Set env for CUDA compute
-        run: echo "CUDA_ARCH=$(nvidia-smi --query-gpu=compute_cap --format=csv,noheader | sed 's/\.//g')" >> $GITHUB_ENV
-      - name: set env for EC_GPU
-        run: echo 'EC_GPU_CUDA_NVCC_ARGS=--fatbin --gpu-architecture=sm_${{ env.CUDA_ARCH }} --generate-code=arch=compute_${{ env.CUDA_ARCH }},code=sm_${{ env.CUDA_ARCH }}' >> $GITHUB_ENV
-      - run: echo "${{ env.EC_GPU_CUDA_NVCC_ARGS}}"
-      # Check that CUDA is installed with a driver-compatible version
-      # This must also be compatible with the GPU architecture, see above link
-      - run: nvcc --version
-      # Check that we can access the OpenCL headers
-      - run: clinfo
-      - name: OpenCL tests
-        run: |
-          cargo nextest run --release --all-features