Arm backend: Added 16x8 tests for VGF

[Christoffer-JL]

Introduced int16a8w for a couple of op tests
on VGF

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

[pytorch-bot]

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• Rolling out OSDC (ARC) runners on pull workflow for PyTorch trunk commits

❌ 3 New Failures, 1 Cancelled Job, 5 Unrelated Failures

As of commit b736d68 with merge base 2eaa16c ():

NEW FAILURES - The following jobs have failed:

• trunk / test-torchao-huggingface-checkpoints (lfm2_5_1_2b, linux.arm64.2xlarge, executorch-ubuntu-22.04-g... / linux-job (gh)
  RuntimeError: Command docker exec -t c4e21d8be3d6f17d178f21d1b5eee270a7cfe0890bb5454afeac9fb2cdae6ed9 /exec failed with exit code 1
• trunk / test-torchao-huggingface-checkpoints (phi_4_mini, linux.arm64.2xlarge, executorch-ubuntu-22.04-gc... / linux-job (gh)
  RuntimeError: Command docker exec -t 5b71408042b99c96dfa19c532d93e1099eafdda3a3b0d4af3edcb2abab59a6f6 /exec failed with exit code 1
• trunk / test-torchao-huggingface-checkpoints (qwen3_4b, linux.arm64.2xlarge, executorch-ubuntu-22.04-gcc1... / linux-job (gh)
  RuntimeError: Command docker exec -t 02c6f6452c04b1ab5a1a28b92932eb75db56fdfad4ec51de9c8e6e02608751eb /exec failed with exit code 1

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

• trunk / test-models-macos-cpu (mv3, xnnpack-quantization-delegation) / macos-job (gh)
  ##[error]The operation was canceled.

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

• pull / unittest / linux / linux-job (gh) (detected as infra flaky with no log or failing log classifier)

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

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

• pull / unittest / macos / macos-job (gh) (trunk failure)
  export/tests/test_target_recipes.py::TestTargetRecipes::test_mv3_model
• pull / unittest / windows / windows-job (gh) (trunk failure)
  ##[error]The operation was canceled.
• pull / unittest-editable / windows / windows-job (gh) (trunk failure)
  ##[error]The operation was canceled.
• trunk / unittest-release / windows / windows-job (gh) (trunk failure)
  ##[error]The operation was canceled.

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[Christoffer-JL]

Failing tests are unrelated