[`ruff`] Restore example code for Python versions before 3.15 (`RUF017`) (#25439)

Summary
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Closes #25436 by restoring the previous `Use instead:` snippet from
before #23789

I thought it would be cool to use the tabs like we have for
pyproject.toml vs ruff.toml snippets, but I wasn't sure if that would
render well in other contexts where we use rule docs and opted just to
have two separate code blocks.