fix(menu): menu horizontal border bottom when dark

[LuciNyan]

[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
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🔗 Related issue link

Closes: #38734

💡 Background and solution

Set the border-bottom of menu-horizontal to 0 in the dark mode in the same way as antd@4.X.

📝 Changelog

Language	Changelog
🇺🇸 English	Fix Menu 1px higher when theme="dark".
🇨🇳 Chinese	修复 Menu 深色 theme 下高度多了 1px 的问题。

☑️ Self-Check before Merge

⚠️ Please check all items below before requesting a reviewing. ⚠️

• 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]

[afc163]

这不是应该放暗色算法里？@zombieJ

[codecov]

Codecov Report

Base: 100.00% // Head: 100.00% // No change to project coverage 👍

Coverage data is based on head (54ffc9b) compared to base (919f7f9).
Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff            @@
##            master    #38741   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          544       544           
  Lines         9368      9352   -16     
  Branches      2650      2651    +1     
=========================================
- Hits          9368      9352   -16     

Impacted Files	Coverage Δ
components/menu/style/theme.tsx	100.00% <100.00%> (ø)
components/menu/index.tsx	100.00% <0.00%> (ø)
components/affix/index.tsx	100.00% <0.00%> (ø)
components/input/index.tsx	100.00% <0.00%> (ø)
components/radio/index.tsx	100.00% <0.00%> (ø)
components/switch/index.tsx	100.00% <0.00%> (ø)
components/button/button.tsx	100.00% <0.00%> (ø)
components/upload/Upload.tsx	100.00% <0.00%> (ø)
components/checkbox/index.tsx	100.00% <0.00%> (ø)
components/mentions/index.tsx	100.00% <0.00%> (ø)
... and 2 more

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