fix(module: menu): fix class name of the expand icon for submenu

[ElderJames]

🤔 This is a ...

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

🔗 Related issue link

💡 Background and solution

📝 Changelog

Language	Changelog
🇺🇸 English	Fixed Menu that class name of the expand icon for submenu
🇨🇳 Chinese	修复 Menu 子菜单展开图标的样式

☑️ 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
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[github-actions]

[codecov]

Codecov Report

Base: 41.59% // Head: 40.14% // Decreases project coverage by -1.45% ⚠️

Coverage data is based on head (26bdfa4) compared to base (bed2028).
Patch coverage: 0.00% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2796      +/-   ##
==========================================
- Coverage   41.59%   40.14%   -1.46%     
==========================================
  Files         544      544              
  Lines       25712    25715       +3     
  Branches      260      260              
==========================================
- Hits        10694    10322     -372     
- Misses      14978    15353     +375     
  Partials       40       40              

Impacted Files	Coverage Δ
components/menu/SubMenu.razor	63.93% <0.00%> (ø)
components/list/ListItemLayout.cs	0.00% <0.00%> (-100.00%)	⬇️
components/list/ListItem.razor	0.00% <0.00%> (-95.31%)	⬇️
components/list/AntList.razor	0.00% <0.00%> (-92.31%)	⬇️
...omponents/form/Validate/Rule/FormRulesValidator.cs	0.00% <0.00%> (-76.93%)	⬇️
components/list/AntList.razor.cs	0.00% <0.00%> (-76.12%)	⬇️
components/list/ListItem.razor.cs	0.00% <0.00%> (-73.08%)	⬇️
components/form/Form.razor.cs	36.02% <0.00%> (-32.30%)	⬇️
components/form/FormItem.razor.cs	43.31% <0.00%> (-29.94%)	⬇️
components/form/Form.razor	71.42% <0.00%> (-28.58%)	⬇️
... and 10 more

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