Remove duplicated test classes

[carmocca]

What does this PR do?

Minor test refactor

Does your PR introduce any breaking changes? If yes, please list them.

None

Before submitting

• [n/a] Was this discussed/approved via a GitHub issue? (not for typos and docs)
• [x] Did you read the contributor guideline, Pull Request section?
• [x] Did you make sure your PR does only one thing, instead of bundling different changes together?
• [n/a] Did you make sure to update the documentation with your changes? (if necessary)
• [n/a] Did you write any new necessary tests? (not for typos and docs)
• [x] Did you verify new and existing tests pass locally with your changes?
• [x] Did you list all the breaking changes introduced by this pull request?
• [n/a] Did you update the CHANGELOG? (not for typos, docs, test updates, or minor internal changes/refactors)

PR review

• [x] Is this pull request ready for review? (if not, please submit in draft mode)
• [x] Check that all items from Before submitting are resolved
• [x] Make sure the title is self-explanatory and the description concisely explains the PR
• [x] Add labels and milestones (and optionally projects) to the PR so it can be classified

cc @borda @akihironitta