Deprecate TRZ

[IAlibay]

Towards #4311

Changes:

• Deprecate the TRZ reader & writer

PR Checklist

• Tests?
• Docs?
• CHANGELOG updated?
• Issue raised/referenced?

Developers certificate of origin

• I certify that this contribution is covered by the LGPLv2.1+ license as defined in our LICENSE and adheres to the Developer Certificate of Origin.

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📚 Documentation preview 📚: https://mdanalysis--4335.org.readthedocs.build/en/4335/

[github-actions]

Linter Bot Results:

Hi @IAlibay! Thanks for making this PR. We linted your code and found the following:

Some issues were found with the formatting of your code.

Code Location	Outcome
main package	⚠️ Possible failure
testsuite	⚠️ Possible failure

Please have a look at the darker-main-code and darker-test-code steps here for more details: https://github.com/MDAnalysis/mdanalysis/actions/runs/6760455762/job/18374242487

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Please note: The black linter is purely informational, you can safely ignore these outcomes if there are no flake8 failures!

[hmacdope]

Nice, LGTM

[IAlibay]

Typical github won't let me unlink the issue - todo: remember to re-open the TRZ issue so we don't close it until it's actually removed.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (540a980) 93.37% compared to head (e3d3673) 93.37%.

Additional details and impacted files

@@            Coverage Diff             @@
##           develop    #4335     +/-   ##
==========================================
  Coverage    93.37%   93.37%             
==========================================
  Files          170      184     +14     
  Lines        22295    23406   +1111     
  Branches      4075     4075             
==========================================
+ Hits         20818    21856   +1038     
- Misses         962     1035     +73     
  Partials       515      515             

Files	Coverage Δ
package/MDAnalysis/coordinates/TRZ.py	84.75% <100.00%> (+0.23%)	⬆️

... and 14 files with indirect coverage changes

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[IAlibay]

Test failure is expecting - merging.