fix(layout-sider): menu-item width is wrong when collapsedWidth is set

[Map1en]

[中文版模板 / Chinese template]

🤔 This is a ...

• New feature
• Bug fix
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🔗 Related issue link

close #30355

💡 Background and solution

当collapsedWidth设置时，内部menu-item的宽度是固定的，不能根据设置的宽度自适应。

📝 Changelog

Language	Changelog
🇺🇸 English	修复当设置collapsedWidth时menu-item宽度错误的问题
🇨🇳 Chinese	Fix the problem that menu-item width is wrong when collapsedWidth is set

☑️ 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

[github-actions]

[codecov]

Codecov Report

Merging #30357 (2344937) into master (60cad5a) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##            master    #30357   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          397       397           
  Lines         7523      7523           
  Branches      2105      2105           
=========================================
  Hits          7523      7523           

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