fix(Layout): 修复 PageContainer 设置 fixedHeader 属性后，样式 ant-pro-page-container-warp 未生效问题

[hqwlkj]

修复之前：

修复之后：

[github-actions]

🎊 PR Preview has been successfully built and deployed to https://pro-components-preview-pr-6078.surge.sh

[codecov]

Codecov Report

Base: 98.80% // Head: 98.80% // Increases project coverage by +0.00% 🎉

Coverage data is based on head (008ba1a) compared to base (e06d908).
Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #6078   +/-   ##
=======================================
  Coverage   98.80%   98.80%           
=======================================
  Files         268      268           
  Lines        7885     7886    +1     
  Branches     2723     2807   +84     
=======================================
+ Hits         7791     7792    +1     
  Misses         94       94           

Impacted Files	Coverage Δ
...ages/layout/src/components/PageContainer/index.tsx	98.13% <ø> (ø)
...layout/src/components/PageContainer/style/index.ts	100.00% <ø> (ø)
packages/field/src/components/Segmented/index.tsx	100.00% <100.00%> (ø)
...ackages/layout/src/components/PageHeader/index.tsx	92.64% <100.00%> (ø)

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