Fix unchecked Result in get_llm_metadata()

[kirklandsign]

Summary:
In get_llm_metadata(), module->get() returns a Result but the old code called
.get() without checking if the result is ok. If the method exists in the model
(checked via method_names.count()) but module->get() still fails, this indicates
a serious issue with the .pte file.

Use ET_UNWRAP to propagate the error instead of silently falling back to
defaults, which could mask .pte corruption.

Differential Revision: D99707695

[pytorch-bot]

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❌ 1 New Failure, 9 Pending

As of commit 36b53a4 with merge base a3a08c1 ():

NEW FAILURE - The following job has failed:

• Cadence Build & Test / cpu-test / test-ops / test-ops (gh)
  examples/cadence/operators/test_g3_ops.py::ATenOpTestCases::test_g3_neg_out_7

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[meta-codesync]

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[Copilot]

Pull request overview

Updates get_llm_metadata() in the LLM runner helpers to correctly handle failures when retrieving metadata values from a Module, avoiding unchecked Result access and surfacing model/.pte issues as errors.

Changes:

• Replace unchecked Result::get() usage on module->get(method_name) with ET_UNWRAP(...) to propagate errors.
• Prevent silently continuing with default metadata when the model claims a metadata method exists but retrieval fails.

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[larryliu0820]

Review automatically exported from Phabricator review in Meta.