[OpenVINOQuantizer] Fix Method to Obtain Quantization Parameters

[anzr299]

Summary

A recent change in NNCF functions to return quantization parameters breaks the OpenVINO quantizer observers.
This PR addresses the issue and also adds backwards support for this problem.

[pytorch-bot]

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❌ 2 New Failures, 2 Unrelated Failures

As of commit b4e17de with merge base 6823b33 ():

NEW FAILURES - The following jobs have failed:

• Lint / lintrunner (gh)
  >>> Lint for backends/openvino/quantizer/observers.py:
• Lint / lintrunner-mypy (gh)
  >>> Lint for backends/openvino/quantizer/observers.py:

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

• pull / unittest-editable / windows / windows-job (gh) (matched win rule in flaky-rules.json)
  ##[error]The operation was canceled.

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

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

• pull / unittest / windows / windows-job (gh) (trunk failure)
  ##[error]The operation was canceled.

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[Copilot]

Pull request overview

Fixes OpenVINO weight-compression observers to handle an NNCF API change where integer quantization now returns a structured object (quantization parameters), while attempting to preserve compatibility with older NNCF behavior.

Changes:

• Adds handling for do_integer_quantization(...) returning a CompressedWeight object (newer NNCF).
• Adds fallback handling for legacy tuple return (q_weight, scale, zp) (older NNCF).
• Introduces a new import for CompressedWeight to support the new return type.

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Pull request overview

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[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated 2 comments.

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