chore: use menu icon less variable

[yoyo837]

🤔 This is a ...

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

🔗 Related issue link

💡 Background and solution

close #19545

📝 Changelog

Language	Changelog
🇺🇸 English
🇨🇳 Chinese	menu icon 使用独立的less 变量

☑️ 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

[netlify]

Deploy preview for ant-design ready!

Built with commit 73d6708

https://deploy-preview-19553--ant-design.netlify.com

[codecov]

Codecov Report

Merging #19553 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master   #19553   +/-   ##
=======================================
  Coverage    97.8%    97.8%           
=======================================
  Files         284      284           
  Lines        7698     7698           
  Branches     2117     2166   +49     
=======================================
  Hits         7529     7529           
  Misses        169      169

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