Add per-node worker sizing for download stages

[praateekmahajan]

Summary

• Add ProcessingStage.num_workers_per_node() and with_(num_workers_per_node=...), with base validation rejecting simultaneous num_workers and per-node sizing.
• Translate per-node sizing in Ray Data, Ray Actor Pool, and Xenna while reusing shared alive-Ray-node helpers.
• Apply default per-node limits to download-like stages and add matching backend/stage tests.

Fixes #2197

Test Plan

• ruff check nemo_curator/stages/base.py nemo_curator/backends/utils.py nemo_curator/backends/xenna/executor.py nemo_curator/backends/ray_data/adapter.py nemo_curator/backends/ray_data/executor.py nemo_curator/backends/ray_actor_pool/utils.py nemo_curator/utils/ray_utils.py nemo_curator/stages/text/download/base/download.py nemo_curator/stages/text/download/common_crawl/download.py nemo_curator/stages/text/download/arxiv/download.py nemo_curator/stages/text/download/wikipedia/download.py nemo_curator/stages/video/io/video_reader.py tests/stages/common/test_base.py tests/backends/test_xenna_executor.py tests/backends/ray_data/test_adapter.py tests/backends/ray_actor_pool/test_executor.py tests/utils/test_ray_utils.py tests/stages/text/download/base/test_download.py tests/stages/text/download/common_crawl/test_download.py tests/stages/text/download/arxiv/test_download.py tests/stages/text/download/wikipedia/test_download.py tests/stages/video/io/test_video_reader.py
• ruff format --check nemo_curator/stages/base.py nemo_curator/backends/utils.py nemo_curator/backends/xenna/executor.py nemo_curator/backends/ray_data/adapter.py nemo_curator/backends/ray_data/executor.py nemo_curator/backends/ray_actor_pool/utils.py nemo_curator/utils/ray_utils.py nemo_curator/stages/text/download/base/download.py nemo_curator/stages/text/download/common_crawl/download.py nemo_curator/stages/text/download/arxiv/download.py nemo_curator/stages/text/download/wikipedia/download.py nemo_curator/stages/video/io/video_reader.py tests/stages/common/test_base.py tests/backends/test_xenna_executor.py tests/backends/ray_data/test_adapter.py tests/backends/ray_actor_pool/test_executor.py tests/utils/test_ray_utils.py tests/stages/text/download/base/test_download.py tests/stages/text/download/common_crawl/test_download.py tests/stages/text/download/arxiv/test_download.py tests/stages/text/download/wikipedia/test_download.py tests/stages/video/io/test_video_reader.py
• pytest tests/stages/common/test_base.py tests/backends/test_xenna_executor.py tests/backends/ray_data/test_adapter.py tests/backends/ray_actor_pool/test_executor.py tests/utils/test_ray_utils.py tests/stages/text/download/base/test_download.py tests/stages/text/download/common_crawl/test_download.py tests/stages/text/download/arxiv/test_download.py tests/stages/text/download/wikipedia/test_download.py tests/stages/text/download/base/test_url_generation.py tests/stages/video/io/test_video_reader.py -q

[copy-pr-bot]

Auto-sync is disabled for draft pull requests in this repository. Workflows must be run manually.

Contributors can view more details about this message here.

[praateekmahajan]

/ok to test 82603dd