chore: apply one theme styles to side nav

[mxschll]

Description

Applies one theme related changes to collapsible sidenav.

Related links, issue #, if available: n/a

How has this been tested?

Locally.

Review checklist

The following items are to be evaluated by the author(s) and the reviewer(s).

Correctness

• Changes include appropriate documentation updates.
• Changes are backward-compatible if not indicated, see CONTRIBUTING.md.
• Changes do not include unsupported browser features, see CONTRIBUTING.md.
• Changes were manually tested for accessibility, see accessibility guidelines.

Security

• If the code handles URLs: all URLs are validated through the checkSafeUrl function.

Testing

• Changes are covered with new/existing unit tests?
• Changes are covered with new/existing integration tests?

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.57%. Comparing base (c6ed749) to head (32a76ad).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4670   +/-   ##
=======================================
  Coverage   97.57%   97.57%           
=======================================
  Files         948      948           
  Lines       30489    30492    +3     
  Branches    11149    11151    +2     
=======================================
+ Hits        29749    29752    +3     
  Misses        693      693           
  Partials       47       47           

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[mxschll]

Even though this is just a dev page, we don't want to see the themed version but the actual version of the side nav in one theme. Hence, removed this part.