Remove tutorials/calibration_flow/ and update stale references

[jerryzh168]

Stack from ghstack (oldest at bottom):

• Remove LinearActivationQuantizedTensor and all related code #4258
• -> Remove tutorials/calibration_flow/ and update stale references #4257

Summary:
Remove the calibration_flow tutorial folder (static_quant.py, gptq_like.py,
awq_like.py) which depended on LinearActivationQuantizedTensor and other
deprecated AQT APIs. Update documentation references that pointed to these
deleted files.

Test Plan:

• Verified no remaining references to calibration_flow/, static_quant.py,
  gptq_like.py, or awq_like.py in the codebase
• Doc links updated to point to remaining valid resources

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/ao/4257

• 📄 Preview Python docs built from this PR

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[andrewor14]

@claude review please

[claude]

Claude finished @andrewor14's task in 1m 5s —— View job

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Review of PR #4257

• Gather context and read the diff
• Review deleted files for any code that should be preserved
• Review documentation updates for correctness
• Verify no remaining stale references in the codebase
• Post review feedback

---

This is a clean removal of deprecated tutorial code and the corresponding documentation updates. The changes look good.

Deleted files: All three deleted files (static_quant.py, gptq_like.py, awq_like.py) imported deprecated/deleted APIs (AffineQuantizedTensor, to_affine_quantized_intx, LinearActivationQuantizedTensor, to_linear_activation_quantized, to_weight_tensor_with_linear_activation_scale_metadata), consistent with the AQT deletion in #4245. Each file already had a TODO: migrate off AffineQuantizedTensor comment, confirming these were known to be stale. No reusable code needs to be preserved — the static quantization tutorial content is already captured inline in docs/source/eager_tutorials/static_quantization.rst.

Documentation updates:

• quantization_overview.rst:144 — Rewording removes the dead link to gptq_like.py and simplifies the sentence to reference Autoround directly. The updated Autoround link now points to blob/main/... which is appropriate for docs.
• static_quantization.rst:8 — Removes the link to the deleted static_quant.py example script. The sentence reads naturally without it since the tutorial is self-contained.
• static_quantization.rst:239 — Removes the closing paragraph's reference to the deleted script and the mention of float8 static quantization. This is fine since that float8 example was also in the deleted file.
• autoround/README.md:41 — Replaces the dead gptq_like.py link with a link to the MultiTensor gist, which is the relevant resource for understanding the flow pattern.

Stale reference check: Grep confirms zero remaining references to calibration_flow/, static_quant.py, gptq_like.py, or awq_like.py in the codebase.

No issues found. LGTM.