Remove strtobool use

[IAlibay]

Simple enough one but it was tripping the Py3.12 tests.

Changes made in this Pull Request:

• Switch from strtobool to a simple check on "true" for the high memory tests.

PR Checklist

• Tests?
• CHANGELOG updated?

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.

---

📚 Documentation preview 📚: https://mdanalysis--4295.org.readthedocs.build/en/4295/

[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	✅ Passed
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/6245624416/job/16954639116

---

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

[codecov]

Codecov Report

Patch and project coverage have no change.

Comparison is base (10b09c9) 93.40% compared to head (a10ace8) 93.40%.

Additional details and impacted files

@@            Coverage Diff             @@
##           develop    #4295     +/-   ##
==========================================
  Coverage    93.40%   93.40%             
==========================================
  Files          170      184     +14     
  Lines        22256    23364   +1108     
  Branches      4071     4071             
==========================================
+ Hits         20789    21824   +1035     
- Misses         951     1024     +73     
  Partials       516      516             

see 14 files with indirect coverage changes

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.