Fix Cortex-M MobileNetV2 dialect test expected op counts

[rascani]

Summary

The test expected 1 dequantize/quantize_per_tensor op each after transforms, but the graph actually produces 2. The extra pair is a requantization boundary between avg_pool2d and linear caused by an unannotated clone_dim_order node blocking FoldAndAnnotateQParamsPass from folding through the view_copy -> clone_dim_order -> linear chain.

This PR was authored with Claude.

Test plan

pytest "backends/cortex_m/test/models/test_mobilenet_v2.py::test_dialect_mv2[mobilenet_v2]"

[pytorch-bot]

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❌ 2 New Failures, 16 Pending, 1 Unrelated Failure

As of commit f5428f4 with merge base f08db65 ():

NEW FAILURES - The following jobs have failed:

• pull / test-samsung-models-linux / linux-job (gh)
  RuntimeError: Command docker exec -t 5a7114d16cc310d403e160e377a6e3998bc6d79c4f0be0b153670d6b760f0c3f /exec failed with exit code 1
• pull / test-samsung-quantmodels-linux / linux-job (gh)
  RuntimeError: Command docker exec -t d6819da8af5572fc73e24d19c8deaf284e6fa9af89a0ceb201eeb5f84f02d219 /exec failed with exit code 1

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

• trunk / test-llama-runner-linux (fp32, xnnpack+custom, linux.2xlarge, executorch-ubuntu-22.04-clang12) / linux-job (gh) (matched linux rule in flaky-rules.json)
  The runner has received a shutdown signal. This can happen when the runner service is stopped, or a manually started runner is canceled.

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