revert: Partially rounded corners for stacked bar charts

[pan-kot]

Description

Reverting PR #2171 due to unexpected performance impact.

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

Attention: Patch coverage is 96.87500% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 95.34%. Comparing base (34b4ff4) to head (5b4765c).

Files	Patch %	Lines
src/mixed-line-bar-chart/utils.ts	94.44%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2190      +/-   ##
==========================================
- Coverage   95.35%   95.34%   -0.02%     
==========================================
  Files         687      687              
  Lines       18407    18382      -25     
  Branches     6161     6150      -11     
==========================================
- Hits        17552    17526      -26     
- Misses        801      802       +1     
  Partials       54       54              

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