fix: Tooltip arrowPointAtCenter 1px shift bug

[afc163]

[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
• Performance optimization
• Enhancement feature
• Internationalization
• Refactoring
• Code style optimization
• Test Case
• Branch merge
• Other (about what?)

🔗 Related issue link

close #31197

💡 Background and solution

📝 Changelog

Language	Changelog
🇺🇸 English	Fix Tooltip arrowPointAtCenter 1px shift bug
🇨🇳 Chinese	修复 Tooltip arrowPointAtCenter 有一像素偏移的问题。

☑️ 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

[github-actions]

[codecov]

Codecov Report

Merging #31201 (6b0833a) into master (4e12007) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master    #31201   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          397       397           
  Lines         7561      7596   +35     
  Branches      2074      2092   +18     
=========================================
+ Hits          7561      7596   +35     

Impacted Files	Coverage Δ
components/tooltip/placements.tsx	100.00% <100.00%> (ø)
components/form/FormItem.tsx	100.00% <0.00%> (ø)

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[github-actions]

Size Change: -4 B (0%)

Total Size: 832 kB

Filename	Size	Change
./dist/antd-with-locales.min.js	341 kB	-2 B (0%)
./dist/antd.min.js	297 kB	-2 B (0%)

ℹ️ View Unchanged

Filename	Size
./dist/antd.compact.min.css	64.2 kB
./dist/antd.dark.min.css	65.5 kB
./dist/antd.min.css	64.4 kB

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