Use STDOUT fallback after FileNotFoundError in gather benchmarks

[GregoryComer]

Summary

The gather_benchmarks job is currently failing on PyTorch Core when running ET CI. This change allows the gather_benchmarks job to gracefully fall back to logging to STDOUT when not running in the expected ET CI environment. This should unblock the ET pin bump in PyTorch.

This is a based on @guangy10's suggestion on pytorch/pytorch#145831 (comment).

Test plan

Validating via CI run.

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/8258

• 📄 Preview Python docs built from this PR

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❗ 1 Active SEVs

There are 1 currently active SEVs. If your PR is affected, please view them below:

• ROCM Infra failures during checkout of PyTorch

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

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/8258

• 📄 Preview Python docs built from this PR

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

❗ 1 Active SEVs

There are 1 currently active SEVs. If your PR is affected, please view them below:

• ROCM Infra failures during checkout of PyTorch

✅ You can merge normally! (1 Unrelated Failure)

As of commit 8d933ca with merge base dad2ba0 ():

FLAKY - The following job failed but was likely due to flakiness present on trunk:

• trunk / test-pybind-build-macos (cmake) / macos-job (gh) (detected as infra flaky with no log or failing log classifier)

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

[guangy10]

Looks good. Now you will need to test this PR by pinning this to the pytorch CI.

To do it, you will need to make sure this PR is NOT created from your fork. After it, you can just pin the commit as how you updated the pinned executorch commit in pytorch