Capture expected deprecation warnings in entry-point tests

[claell]

Summary

• Capture the expected DeprecationWarning in legacy/new parameter conflict tests.
• Retain the existing ValueError and message assertions.
• Make the complete suite pass with warnings treated as errors.

Closes #581.

Validation

• pytest -p no:cacheprovider -W error: 2,576 passed, 12 skipped.
• Complete pre-commit hook suite: passed.

Review note

This is a test-only change. It makes warnings already emitted by the intended conflict path explicit rather than suppressing warnings globally.

AI assistance

This pull request was prepared with ChatGPT Codex using GPT-5.6 Sol with high reasoning effort. Codex assisted with warning analysis, branch isolation, and validation. Automated validation is not a substitute for maintainer review.

[MiWeiss]

Hi @claell — same note across all of your July 16 issues and PRs (#567–#597), apologies for the repetition.

Closing this. Passing CI isn't evidence the underlying claim is real — it just means generated tests match generated code. The batch's timing, structure, and forward-referenced numbers point to this being AI-generated rather than manually found and checked, and reviewing it properly would take more effort than a targeted pass over the parser myself.

If this fixes something you actually hit: open a small, human-verified PR against a reopened issue with a real repro, and I'll review it in good faith. Any nontrivial design or API choice needs to be discussed and agreed first, not decided inside a PR. Please disclose and verify AI-assisted work before submitting going forward.