rust: Fix query formatting for pgwire

[def-]

Minimal alternative to #35191
We can merge this first, whether we want to merge the other or not.

[github-actions]

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[def-]

Ready for review

[ggevay]

Thank you!

(Btw. the PR description says "Minimal alternative to #35198", but that PR is already merged, so maybe you meant to link a different PR?)

[def-]

Thanks, fixed: #35191