Unload test modules

[iSazonov]

PR Summary

Fix #11058

PR Context

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  • N/A or can only be tested interactively
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[anmenaga]

@iSazonov Thank you for doing this; it is a good step in increasing stability of the tests.

[ghost]

🎉v7.0.0-preview.6 has been released which incorporates this pull request.:tada:

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