Fix AttributeError when torchao ops are not registered

[elpdumont]

Summary:
The _QUANT_PRIMITIVES list initialization in util.py catches ImportError when torchao is not installed, but fails to catch AttributeError when torchao is installed but the operators (dequantize_affine, quantize_affine, choose_qparams_affine) are not registered.

This causes import failures in environments where torchao is available but an older version is used that doesn't have these operators registered.

The fix adds AttributeError to the exception handler alongside ImportError.

Differential Revision: D95735505

[pytorch-bot]

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❌ 3 New Failures

As of commit a133516 with merge base 122fdef ():

NEW FAILURES - The following jobs have failed:

• pull / test-llama-runner-qnn-linux (fp32, qnn_16a16w, qnn) / linux-job (gh)
  RuntimeError: Command docker exec -t 9ef14359bb29d33578598beb9ce2edb6b7c7164de56afbf807b210ce7b1cacd4 /exec failed with exit code 9
• pull / test-samsung-models-linux / linux-job (gh)
  RuntimeError: Command docker exec -t f6a6d88504e991a1410c159ee2ebe32420140517d0ac827ace7a606707560a14 /exec failed with exit code 1
• pull / test-samsung-quantmodels-linux / linux-job (gh)
  RuntimeError: Command docker exec -t 6ce5d43f0ec7ddf4a4157bf46d58fb5426928f3323e6231887330fac5cc6ba32 /exec failed with exit code 1

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[meta-codesync]

@elpdumont has exported this pull request. If you are a Meta employee, you can view the originating Diff in D95735505.

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