Remove a redundant library from the test setup (#5587)

# What does this implement/fix?

Our test workflow asked apt for the chromaprint library, with a comment
saying the AcoustID provider imports it. That is no longer true: since
#5434 the provider no longer imports it at module level, and the tests
run against a fake fingerprinter. Nothing in the test run needs the
library.

Asking for it explicitly was redundant anyway — ffmpeg already pulls it
in — so the test environment is unchanged. This just drops the leftover
request and the comment that gave the wrong reason for it.

Checked by running the full test suite with the chromaprint import
blocked: identical results, and none of the skips relate to chromaprint.

- Removed the redundant chromaprint entry from the test workflow, along
with the outdated comment
- Noted why PortAudio is still asked for: without it some local audio
tests skip instead of running

**Related issue (if applicable):**

- n/a

## Types of changes

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- [ ] Bugfix (non-breaking change which fixes an issue) — `bugfix`
- [ ] New feature (non-breaking change which adds functionality) —
`new-feature`
- [ ] Enhancement to an existing feature — `enhancement`
- [ ] New music/player/metadata/plugin provider — `new-provider`
- [ ] Breaking change (fix or feature that would cause existing
functionality to not work as expected) — `breaking-change`
- [ ] Refactor (no behaviour change) — `refactor`
- [ ] Documentation only — `documentation`
- [ ] Maintenance / chore — `maintenance`
- [X] CI / workflow change — `ci`
- [ ] Dependencies bump — `dependencies`

## Checklist

- [X] The code change is tested and works locally.
- [X] `pre-commit run --all-files` passes.
- [X] `pytest` passes, and tests have been added/updated under `tests/`
where applicable.
- [ ] For changes to shared models, the companion PR in
`music-assistant/models` is linked.
- [ ] For changes affecting the UI, the companion PR in
`music-assistant/frontend` is linked.
- [X] I have read and complied with the project's [AI
Policy](https://github.com/music-assistant/.github/blob/main/AI_POLICY.md)
for any AI-assisted contributions.
- [ ] I have [raised a PR against the documentation
repository](https://github.com/music-assistant/music-assistant.io/blob/main/CONTRIBUTING.md)
targeting the main or beta branch as appropriate.