fix: List bordered and split props conflict

[MXWXZ]

🤔 This is a ...

• New feature
• Bug fix
• Site / document update
• Component style update
• TypeScript definition update
• Refactoring
• Code style optimization
• Test Case
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🔗 Related issue link

💡 Background and solution

When List props split=true it already has .ant-list-split class that add the split line, while bordered=true will add .ant-list-bordered .ant-list-item that add the split line too.

So when split=false and bordered=true, the split line will still exist.

Solution: remove the split line in .ant-list-bordered .ant-list-item.
sandbox

📝 Changelog

Language	Changelog
🇺🇸 English	List bordered and split props conflict
🇨🇳 Chinese	List组件bordered和split属性冲突

☑️ Self Check before Merge

• Doc is updated/provided or not needed
• Demo is updated/provided or not needed
• TypeScript definition is updated/provided or not needed
• Changelog is provided or not needed

[ant-design-bot]

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[codecov]

Codecov Report

Merging #21784 into master will not change coverage.
The diff coverage is n/a.

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##           master   #21784   +/-   ##
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  Coverage   97.88%   97.88%           
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  Files         305      305           
  Lines        6999     6999           
  Branches     1884     1884           
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  Hits         6851     6851           
  Misses        148      148

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