fix: Correct theme import for Descriptions element

[lisenenkov]

With @import '../../style/themes/default'; theme customization doesn't work

[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
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🔗 Related issue link

💡 Background and solution

📝 Changelog

Language	Changelog
🇺🇸 English	Fix Descriptions wrong styling import.
🇨🇳 Chinese	修复 Descriptions 单独引入样式丢失的问题。

☑️ 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 #30602 (e45104a) into master (7c06c1b) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##            master    #30602   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          397       397           
  Lines         7521      7521           
  Branches      2050      2102   +52     
=========================================
  Hits          7521      7521           

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