Fix Context Parallelism doc

[a120092009]

What does this PR do?

Fix error in Context Parallelism doc

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@yiyixuxu @sayakpaul Anyone in the community is free to review the PR once the tests have passed. Feel free to tag members/contributors who may be interested in your PR.

Use origin code in the CP doc, error will occur on A100-PCIE-80G with nvcr.io/nvidia/pytorch:25.10-py3

After the fix, code can run correcly

[HuggingFaceDocBuilderDev]

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