fix: Select with '' string value align issue

[zombieJ]

🤔 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

fix #21871

💡 Background and solution

📝 Changelog

Language	Changelog
🇺🇸 English	Fix Select with empty string value align issue.
🇨🇳 Chinese	修复 Select 在空字符串值时的样式对齐问题。

☑️ 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

[zombieJ]

#20538 切换后不需要额外的 line-height，转之做伪类对齐即可。

[ant-design-bot]

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[codecov]

Codecov Report

Merging #21880 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master   #21880   +/-   ##
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  Coverage   97.97%   97.97%           
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  Files         305      305           
  Lines        6999     6999           
  Branches     1929     1928    -1     
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  Hits         6857     6857           
  Misses        142      142

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