Arm backend: Enable Swin2SR TOSA ref tests

[usamahz]

Summary:

• Enable Swin2SR FP and INT TOSA pipelines to run through the reference model.
• Keep quantized VGF runtime execution Linux-only until Darwin VKML validation is available.
• Record current Swin2SR partition boundaries and track delegation gaps in MLETORCH-2163.

Test Plan:

• lintrunner on test_swin2sr_arm.py
• backends/arm/scripts/pre-push

cc @digantdesai @freddan80 @per @zingo @oscarandersson8218 @mansnils @Sebastian-Larsson @robell @rascani

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/19771

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❌ 1 New Failure, 4 Unrelated Failures

As of commit f03d50e with merge base c5e3e2b ():

NEW FAILURE - The following job has failed:

• pull / test-multimodal-linux (gemma3-4b) / linux-job (gh)
  RuntimeError: Command docker exec -t 8029051b8c097179145e9d2275477ac425d43fb2c636ff98ab7c7bfa867c4b45 /exec failed with exit code 139

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

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

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

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

• pull / test-static-llama-qnn-linux (stories_110m) / linux-job (gh) (trunk failure)
  test_llama_stories_110m
• pull / unittest / macos / macos-job (gh) (trunk failure)
  ##[error]The operation was canceled.
• trunk / unittest-release / macos / macos-job (gh) (trunk failure)
  ##[error]The operation was canceled.

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[usamahz]

/easycla