Rename comment system test file and class

[Anushre2005]

This PR renames the comment system test file and updates the test class name
to match the filename and follow the project’s naming conventions.

Fixes #11620

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[Anushre2005]

@publiclab/reviewers Hi 👋 This is my first open-source contribution.
I’ve completed the requested changes — please let me know if anything needs updating.
Thank you!

[Anushre2005]

Hi 👋
The CI failures appear to be related to GitHub Actions / Codecov infrastructure
(deprecated actions and rate limiting), and not caused by this change.
Please let me know if you’d like me to update anything on my end. Thanks!

[Anushre2005]

Hi maintainers 👋
It looks like the CI is failing due to the repository workflow using the deprecated
actions/upload-artifact@v2, which GitHub now blocks automatically.

The failures seem unrelated to the PR changes themselves.
Happy to submit a workflow-fix PR (upgrade to @v4) if that’s helpful.
Thanks!