switch docs builds to RTX Pro 6000 #333

Description

RAPIDS projects generally need a GPU in their docs builds because things like Sphinx autosummary require actually import-ing the libraries, and many of the libraries require a GPU at runtime.

Today, projects are using the custom-job shared workflow and hard coding a GPU type, mostly L4.

  docs-build:
    uses: rapidsai/shared-workflows/.github/workflows/custom-job.yaml@main
    if: fromJSON(needs.changed-files.outputs.changed_file_groups).build_docs
    with:
      build_type: pull-request
      node_type: "gpu-l4-latest-1"
      arch: "amd64"
      container_image: "rapidsai/ci-conda:26.10-latest"
      script: "ci/build_docs.sh"

(example from NVIDIA/cuml)

L4 runners are heavily used in the shared CI runner system we use right now, which can result in long queue lines:

Look how often they've been 100% utilized in the last 7 days:

We'd like to switch to a less-busy runner type, such as RTX Pro 6000:

Benefits of this work

• better utilization of shared CI resources
• improved end-to-end CI time via less time stuck in "queued"

Acceptance Criteria

• all RAPIDS projects using GPU runners to build docs in CI use RTX Pro 6000 runners

Approach

Centrallize that configuration in shared-workflows:

• shared-workflows (compute-matrix: add 'docs-build' matrix, switch docs builds to RTX PRO 6000 shared-workflows#627)

Test repos:

• cucim (docs-build: switch to RTX Pro 6000 cucim#1156)
• cugraph-docs (docs-build: switch to RTX Pro 6000 cugraph-docs#229)
• cuml (docs-build: switch to RTX Pro 6000 NVIDIA/cuml#8555)

Remaining repos (GitHub search):

• cudf (docs-build: use shared 'build-docs' matrix NVIDIA/cudf#24102)
• cugraph (docs-build: switch to RTX Pro 6000 cugraph#5662)
• cugraph-gnn (docs-build: make use of 'cpu8' runners explicit cugraph-gnn#540)
• cuvs (docs-build: switch to RTX Pro 6000, add changed-files filter NVIDIA/cuvs#2584)
• dask-cuda (docs-build: switch to RTX Pro 6000 dask-cuda#1684)
• kvikio (docs-build: switch to RTX Pro 6000 kvikio#1066)
• nvforest (docs-build: switch to RTX Pro 6000 nvforest#220)
• raft (docs-build: switch to RTX Pro 6000 NVIDIA/raft#3147)
• rapids-cmake (docs-build: switch to RTX Pro 6000 rapids-cmake#1086) (unnecessary: using CPU runners)
• rapidsmpf (docs-build: switch to RTX Pro 6000 rapidsmpf#1210) (unnecessary: using CPU runners)
• rmm (docs-build: switch to RTX Pro 6000 rmm#2542)
• ucxx (docs-build: switch to RTX Pro 6000 ucxx#758)

Notes

related: #322