Migrate amd64 custom CI jobs from L4 to RTX PRO 6000 #322

Migrate custom GitHub Actions jobs on amd64 from gpu-l4-latest-1 to gpu-rtxpro6000-latest-1 in each repository's .github/workflows/{build,pr,test}.yaml files.

This change helps rebalance CI capacity and uses the fastest hardware available for these jobs.

Repositories requiring changes:

• NVIDIA/cuml
• NVIDIA/cuvs
• rapidsai/cugraph
• rapidsai/kvikio
• rapidsai/rapidsmpf
• rapidsai/rmm

NVIDIA/cudf was completed in NVIDIA/cudf#23878.

Documentation builds will remain on L4, and will be updated by rapidsai/shared-workflows#627. ARM64 jobs will also remain on L4 because RTX PRO 6000 runners are only available for amd64.

Pull requests:

• CI: Migrate custom jobs to RTX PRO 6000 NVIDIA/cuml#8561
• CI: Migrate custom jobs to RTX PRO 6000 NVIDIA/cuvs#2554
• CI: Migrate custom jobs to RTX PRO 6000 cugraph#5647
• CI: Migrate custom jobs to RTX PRO 6000 kvikio#1060
• CI: Migrate custom jobs to RTX PRO 6000 rapidsmpf#1198
• CI: Migrate custom jobs to RTX PRO 6000 rmm#2539