Build QNN backend tests with EXTENSION_TENSOR, mark option as required

[pytorchbot]

The QNN backend references extension_tensor and thus requires it to be built. This PR makes two changes:

• Build extension_tensor in the backend test flow (unbreaks QNN jobs).
• Mark the option as required to build QNN to give a nicer error message.

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/18148

• 📄 Preview Python docs built from this PR

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

❌ 16 New Failures, 196 Pending, 3 Unrelated Failures

As of commit 1404529 with merge base 8c0a60b ():

NEW FAILURES - The following jobs have failed:

• Build Presets / windows (pybind) / build (gh)
  The process 'C:\Program Files\Git\cmd\git.exe' failed with exit code 1
• Build Presets / windows (windows) / build (gh)
  The process 'C:\Program Files\Git\cmd\git.exe' failed with exit code 1
• nightly / link-check / lint-urls (gh)
• nightly / link-check / lint-xrefs (gh)
  Process completed with exit code 128.
• pull / unittest / windows / windows-job (gh)
  The process 'C:\Program Files\Git\cmd\git.exe' failed with exit code 1
• pull / unittest-editable / windows / windows-job (gh)
  The process 'C:\Program Files\Git\cmd\git.exe' failed with exit code 1
• Test Metal Backend / export-model-metal-artifact (nvidia, parakeet-tdt, non-quantized) / macos-job (gh)
  RuntimeError: Command bash /Users/ec2-user/runner/_work/_temp/exec_script failed with exit code 1
• trunk / test-models-windows (emformer_transcribe, portable) / windows-job (gh)
  The process 'C:\Program Files\Git\cmd\git.exe' failed with exit code 1
• trunk / test-models-windows (emformer_transcribe, xnnpack-q8) / windows-job (gh)
  The process 'C:\Program Files\Git\cmd\git.exe' failed with exit code 1
• trunk / test-models-windows (mobilebert, portable) / windows-job (gh)
  The process 'C:\Program Files\Git\cmd\git.exe' failed with exit code 1
• trunk / test-models-windows (mobilebert, xnnpack-q8) / windows-job (gh)
  The process 'C:\Program Files\Git\cmd\git.exe' failed with exit code 1
• trunk / test-models-windows (mv3, xnnpack-q8) / windows-job (gh)
  The process 'C:\Program Files\Git\cmd\git.exe' failed with exit code 1
• trunk / test-models-windows (vit, portable) / windows-job (gh)
  The process 'C:\Program Files\Git\cmd\git.exe' failed with exit code 1
• trunk / test-models-windows (vit, xnnpack-q8) / windows-job (gh)
  The process 'C:\Program Files\Git\cmd\git.exe' failed with exit code 1
• trunk / unittest-release / windows / windows-job (gh)
  The process 'C:\Program Files\Git\cmd\git.exe' failed with exit code 1
• Windows MSVC Build / build-windows-msvc / windows-job (gh)
  The process 'C:\Program Files\Git\cmd\git.exe' failed with exit code 1

FLAKY - The following jobs failed but were likely due to flakiness present on trunk:

• trunk / test-models-windows (mv3, portable) / windows-job (gh) (detected as infra flaky with no log or failing log classifier)
• trunk / test-models-windows (resnet50, portable) / windows-job (gh) (detected as infra flaky with no log or failing log classifier)
• trunk / test-models-windows (resnet50, xnnpack-q8) / windows-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.