Remove unused fused attention workspace optimization control

[ptrendx]

Description

Remove the already unused workspace optimization control - environment variable and the tests.

Type of change

• Documentation change (change only to the documentation, either a fix or a new content)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Infra/Build change
• Code refactoring

Changes

Please list the changes introduced in this PR:

• Removed the workspace opt control from tests
• Removed the mention of the environment variable

Checklist:

• I have read and followed the contributing guidelines
• The functionality is complete
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[ptrendx]

/te-ci pytorch

[greptile-apps]

Greptile Summary

This PR removes the unused fused-attention workspace optimization control. The main changes are:

• Removed the workspace environment variable from the env-var docs.
• Removed workspace optimization guidance from the attention example notebook.
• Dropped the workspace option from attention examples, benchmarks, and tests.
• Removed the old Python-side environment mapping and unused C++ descriptor field.

Confidence Score: 5/5

This looks safe to merge.

• No blocking issues found in the changed code.

Important Files Changed

Filename	Overview
transformer_engine/pytorch/attention/dot_product_attention/dot_product_attention.py	Removes the obsolete workspace environment mapping and related docstring text.
tests/pytorch/attention/test_attention.py	Removes the workspace option from attention test parameters and helper calls.
benchmarks/attention/benchmark_attention.py	Updates benchmark attention helper calls after removing the workspace option.
docs/examples/attention/example_attention.py	Updates the attention example helper calls after removing the workspace option.
docs/envvars.rst	Removes the obsolete workspace environment variable entry.
docs/examples/attention/attention.ipynb	Removes the obsolete workspace optimization guidance from the attention notebook.
transformer_engine/common/fused_attn/utils.h	Removes the unused fused-attention descriptor that carried the workspace option.

_{Reviews (2): Last reviewed commit: "Merge branch 'main' into pr_remove_works..." | Re-trigger Greptile}

[ptrendx]

/te-ci pytorch