fix: button loading style(#17569)

[ghost]

🤔 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?)

👻 What's the background?

close #17569

💡 Solution

📝 Changelog

Language	Changelog
🇺🇸 English	add transition for the span inside Button
🇨🇳 Chinese	为Button里的span添加transition

☑️ Self Check before Merge

• 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

[netlify]

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Built with commit 001384a

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[codecov]

Codecov Report

Merging #17596 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master   #17596   +/-   ##
=======================================
  Coverage   96.04%   96.04%           
=======================================
  Files         267      267           
  Lines        7430     7430           
  Branches     2073     2073           
=======================================
  Hits         7136     7136           
  Misses        292      292           
  Partials        2        2

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