style: optimize cascader rtl style

[xrkffgg]

[中文版模板 / Chinese template]

🤔 This is a ...

• New feature
• Bug fix
• Site / documentation update
• Demo update
• Component style update
• TypeScript definition update
• Bundle size optimization
• Perfermance optimization
• Refactoring
• Code style optimization
• Test Case
• Branch merge
• Other (about what?)

🔗 Related issue link

💡 Background and solution

Before

After

📝 Changelog

Language	Changelog
🇺🇸 English	Fix Cascader dropdown style in RTL.
🇨🇳 Chinese	优化 Cascader RTL 模式下拉框的样式。

☑️ Self Check before Merge

⚠️ Please check all items below before review. ⚠️

• 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

[xrkffgg]

横线 可以直接看出来，border-radius 太小，看不太出来。

[xrkffgg]

话说 GitHub 换 UI 了啊

[ant-design-bot]

[ant-design-bot]

[yoyo837]

我一直想研究下他们的缓存处理机制

[yoyo837]

好像是多页的，fetch加载非首页。

[xrkffgg]

评论的时间，Edit 的历史

好多地方 都值得研究啊 😂😂

[codecov]

Codecov Report

Merging #24520 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master   #24520   +/-   ##
=======================================
  Coverage   99.12%   99.12%           
=======================================
  Files         363      363           
  Lines        7235     7235           
  Branches     2018     1970   -48     
=======================================
  Hits         7172     7172           
  Misses         63       63           

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