Run XNNPACK passes with backed_size_oblivious

[GregoryComer]

Summary:
Run XNNPACK backend-specific passes with backed_size_oblivious=True. This prevents unwanted guards and shape narrowing introduced by ATen backend selection.

This fixes a case where the decompose batch norm pass narrows dynamic batch range because the batchnorm -> pointwise conv rewrite triggers an ATen guard. I added a test which previously reproed the issue and now passes with this change.

Differential Revision: D102676211

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/19262

• 📄 Preview Python docs built from this PR

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

❌ 4 New Failures, 1 Cancelled Job, 2 Unrelated Failures

As of commit 447b770 with merge base a7e44bf ():

NEW FAILURES - The following jobs have failed:

• pull / unittest / linux / linux-job (gh)
  backends/xnnpack/test/ops/test_batch_norm.py::TestBatchNorm::test_fp32_batch_norm_nc_dynamic_batch
• pull / unittest / windows / windows-job (gh)
  backends/xnnpack/test/ops/test_batch_norm.py::TestBatchNorm::test_fp32_batch_norm_nc_dynamic_batch
• pull / unittest-editable / linux / linux-job (gh)
  backends/xnnpack/test/ops/test_batch_norm.py::TestBatchNorm::test_fp32_batch_norm_nc_dynamic_batch
• pull / unittest-editable / windows / windows-job (gh)
  backends/xnnpack/test/ops/test_batch_norm.py::TestBatchNorm::test_fp32_batch_norm_nc_dynamic_batch

CANCELLED JOB - The following job was cancelled. Please retry:

• pull / unittest-buck / macos / macos-job (gh)

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 / macos / macos-job (gh) (trunk failure)
  ##[error]The operation was canceled.
• pull / unittest-editable / macos / macos-job (gh) (trunk failure)
  ##[error]The operation was canceled.

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

[meta-codesync]

@GregoryComer has exported this pull request. If you are a Meta employee, you can view the originating Diff in D102676211.

[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.