chore: Remove duplicate imports in test code

[neilconway]

Which issue does this PR close?

N/A

Rationale for this change

clippy doesn't warn about use statements that re-import an item that is already available via a glob import (use super::*), but in many cases the use statement is redundant and can be safely removed. In particular, there was a lot of test code that did both use super::* and also imported items that were imported by the module under test; the test-specific import can be safely removed.

What changes are included in this PR?

• Mechanical removal of duplicate imports between test code and code under test

Are these changes tested?

Yes, via cargo check and cargo clippy

Are there any user-facing changes?

No.

[neilconway]

@martin-g I was curious why clippy didn't catch the duplicate imports in #20804; turns out that there are a bunch of other duplicate imports we can cleanup.

[martin-g]

I am also not aware of any clippy setting to warn about such "duplicates".
I am curious what command did you use to identify the imports removed in this PR ?

[neilconway]

I am curious what command did you use to identify the imports removed in this PR ?

I first asked Claude Code to see if it could do it; it was a bit slow and unreliable doing it itself, but eventually it decided to write a Python script (attached) that seems like it works pretty well.
fix_redundant_imports.py

[alamb]

This is great -- thank you @neilconway and @martin-g