[MLPerf 6.1][GRPO] Update Qwen3.5 reference assets

[jepio]

Summary

During dataset publishing to MLCommons storage we identified entries that had different behavior between architectures or were fundamentally broken. The result is that the number of datasets in the training and validation set slightly changed, without impacting convergence behavior of the benchmark.

We are also proposing a change to the reference configuration to reduce command and test timeouts from 300/180 to 60/60. These don't affect correctness/convergence but prevent training stalls and allow for better submissions.

Detailed changes in this PR are:

• Documents MLCommons storage as the primary source for the qualified Qwen3.5 checkpoint, dataset, and SIF images.
• Keeps the source preparation and build instructions as optional alternatives.
• Updates the qualified dataset identities, task counts, runtime settings, and NeMo-RL submodule revision.
• Links the NeMo-RL updated mlperf-training-qwen35-main branch.

Related compliance checker update:

• Update Qwen3.5 validation sample count logging#475.

[github-actions]

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[ShriyaRishab]

Why is the RL version different?

[jepio]

• dataset preparation scripts have been updated
• documentation has been updated
• test/command timeout update in the configuration

this shows the diff: NVIDIA-NeMo/RL@3fca04c...644f370

[RissyRan]

Thanks for the change and proposal! Have 2 questions:

1. Similar one about 251 samples in validation in Update Qwen3.5 validation sample count logging#475
2. What're are actual train and validation test/command timeout in reference runs?