Refactor quantizer: Only replace with per-tensor variants

[DrJessop]

Summary:
In our previous flow, we would replace ops with default variants, have a special fusion pass which constructs singleton tensors for a variety of fused quantized ops, and then we would call a replace ops to turn them into per-tensor-variants.

I confirmed this was for legacy reasons, so a cleanup was much due.

This diff also fixes any ref implementations during the refactor.

Reviewed By: zonglinpeng

Differential Revision: D83873738

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/14974

• 📄 Preview Python docs built from this PR

Note: Links to docs will display an error until the docs builds have been completed.

❌ 7 New Failures, 3 Pending, 2 Unrelated Failures

As of commit f84f831 with merge base 3591604 ():

NEW FAILURES - The following jobs have failed:

• pull / test-qnn-wheel-packages-linux (3.10) / linux-job (gh)
  RuntimeError: Command docker exec -t 297301d1134feab0072b736c043d0f312df73d9b10c19c863255b94c306e6591 /exec failed with exit code 1
• pull / test-qnn-wheel-packages-linux (3.11) / linux-job (gh)
  RuntimeError: Command docker exec -t 1143182cdeee6c4f973722ec91196a98ac38a534e9836db7368ed8e3647c9bb3 /exec failed with exit code 1
• pull / test-qnn-wheel-packages-linux (3.12) / linux-job (gh)
  RuntimeError: Command docker exec -t c268dab6438c90b6bcc7a69e1630184e34466ca5ecd82a1816d0f88b995f340c /exec failed with exit code 1
• pull / test-samsung-models-linux / linux-job (gh)
  RuntimeError: Command docker exec -t 629b8a0d8e0933879bc8a281ee14cf4e4cf3a13cc34d6eba84d666683673e9dc /exec failed with exit code 1
• pull / unittest / macos / macos-job (gh)
  export/tests/test_target_recipes.py::TestTargetRecipes::test_linear_model
• pull / unittest-editable / macos / macos-job (gh)
  export/tests/test_target_recipes.py::TestTargetRecipes::test_mv3_model
• Test CUDA Builds / test-voxtral-cuda-e2e / linux-job (gh)
  RuntimeError: Command docker exec -t ca04ed5fa003d36bb31d101b0215b5573373e4c61a3c56bd63bb29810b850b5e /exec failed with exit code 2

BROKEN TRUNK - The following jobs failed but were present on the merge base:

👉 Rebase onto the `viable/strict` branch to avoid these failures

• pull / unittest / windows / windows-job (gh) (trunk failure)
  Process completed with exit code 1.
• pull / unittest-editable / windows / windows-job (gh) (trunk failure)
  Process completed with exit code 1.

This comment was automatically generated by Dr. CI and updates every 15 minutes.

[meta-codesync]

@DrJessop has exported this pull request. If you are a Meta employee, you can view the originating Diff in D83873738.

[github-actions]

This PR needs a release notes: label

If your change should be included in the release notes (i.e. would users of this library care about this change?), please use a label starting with release notes:. This helps us keep track and include your important work in the next release notes.

To add a label, you can comment to pytorchbot, for example
@pytorchbot label "release notes: none"

For more information, see
https://github.com/pytorch/pytorch/wiki/PyTorch-AutoLabel-Bot#why-categorize-for-release-notes-and-how-does-it-work.