test: allow recursion in testing

[redyetidev]

This pull request introduces recursion to the test runner. Previous attempts were unsuccessful due to issues in certain directories that did not handle recursion correctly. This PR specifically enables recursion for the parallel and sequential directories.

Other testing directories haven't been changed, as enabling recursion with them ending in coverage errors.

Fixes #52901 (Failed attempt) Fixes #53410 (Failed attempt) Fixes #53309 (Failed attempt)

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I apologize for the three failed PRs, coverage issues are very finicky, especially when the test files and coverage files are all being modified by different commits at the same time.

After narrowing down what works, this is the final and correct implementation