GH-103805: Lib test f541 linting issue fix (#103812)

This PR makes some minor linting adjustments to the Lib/test module
caught by [ruff](https://github.com/charliermarsh/ruff). The adjustments
are all related to the `F541 f-string without any placeholders` issue.

Issue: https://github.com/python/cpython/issues/103805

<!-- gh-issue-number: gh-103805 -->
* Issue: gh-103805
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Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com>
Co-authored-by: Gregory P. Smith <greg@krypto.org>