revert: Revert "chore: Apply flashbar new style in one-theme (#4671)"

[jperals]

This reverts commit f91a59e.

Description

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

How has this been tested?

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 (9c66790) to head (bd16899).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4683      +/-   ##
==========================================
- Coverage   97.57%   97.57%   -0.01%     
==========================================
  Files         948      948              
  Lines       30496    30495       -1     
  Branches    11155    11154       -1     
==========================================
- Hits        29756    29755       -1     
  Misses        733      733              
  Partials        7        7              

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