improvement: Form default locale

[hengkx]

🤔 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

close #23148

💡 Background and solution

📝 Changelog

Language	Changelog
🇺🇸 English	Form add zh_CN locale
🇨🇳 Chinese	Form增加中文文案

☑️ 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

[ant-design-bot]

[codesandbox-ci]

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[codecov]

Codecov Report

Merging #23165 into master will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master   #23165      +/-   ##
==========================================
+ Coverage   98.35%   98.36%   +0.01%     
==========================================
  Files         365      365              
  Lines        7285     7291       +6     
  Branches     1998     1953      -45     
==========================================
+ Hits         7165     7172       +7     
+ Misses        120      119       -1     

Impacted Files	Coverage Δ
components/locale-provider/index.tsx	100.00% <ø> (ø)
components/config-provider/index.tsx	100.00% <100.00%> (+4.16%)	⬆️
components/locale/zh_CN.tsx	100.00% <100.00%> (ø)

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[zombieJ]

加个 test case