Update CI workflows a bit

[IAlibay]

Removing the cudatoolkit shims since they don't do anything else.
Also a bit of tidying up.

LLM / AI generated code disclosure

LLMs or other AI-powered tools (beyond simple IDE use cases) were used in this contribution: no

PR Checklist

• Issue raised/referenced?
• Tests updated/added?
• Documentation updated/added?
• package/CHANGELOG file updated?
• Is your name in package/AUTHORS? (If it is not, add it!)
• LLM/AI disclosure was updated.

Developers Certificate of Origin

I certify that I can submit this code contribution as described in the Developer Certificate of Origin, under the MDAnalysis LICENSE.

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📚 Documentation preview 📚: https://mdanalysis--5286.org.readthedocs.build/en/5286/

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.82%. Comparing base (2f240fb) to head (d7dba6a).
⚠️ Report is 2 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #5286      +/-   ##
===========================================
- Coverage    93.82%   93.82%   -0.01%     
===========================================
  Files          180      180              
  Lines        22477    22477              
  Branches      3191     3191              
===========================================
- Hits         21090    21089       -1     
- Misses         924      925       +1     
  Partials       463      463              

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[orbeckst]

Lgtm! Thx!!