fix(table): table初始化时，fixed的阴影效果没有出现

[LoopZhou]

🤔 这个 PR 的性质是？

• 日常 bug 修复
• 新特性提交
• 文档改进
• 演示代码改进
• 组件样式/交互改进
• CI/CD 改进
• 重构
• 代码风格优化
• 测试用例
• 分支合并
• 其他

🔗 相关 Issue

Fixes #909

💡 需求背景和解决方案

table初始化时，fixed的阴影效果没有出现
排查是shadowLastScrollLeft 初始化时设置为0， 而 scrollLeft 也为0，导致初始化时没有更新固定列阴影

📝 更新日志

• fix(table): table初始化时，fixed的阴影效果没有出现

• 本条 PR 不需要纳入 Changelog

☑️ 请求合并前的自查清单

⚠️ 请自检并全部勾选全部选项。⚠️

• 文档已补充或无须补充
• 代码演示已提供或无须提供
• TypeScript 定义已补充或无须补充
• Changelog 已提供或无须提供

[github-actions]

[codecov-commenter]

Codecov Report

Merging #922 (2a8806d) into develop (a0db0df) will increase coverage by 2.64%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           develop     #922      +/-   ##
===========================================
+ Coverage    57.56%   60.20%   +2.64%     
===========================================
  Files          346      376      +30     
  Lines        12828    14313    +1485     
  Branches      2405     2666     +261     
===========================================
+ Hits          7384     8617    +1233     
- Misses        5200     5433     +233     
- Partials       244      263      +19     

Impacted Files	Coverage Δ
src/affix/affix.tsx	28.57% <0.00%> (-37.51%)	⬇️
src/swiper/props.ts	68.75% <0.00%> (-31.25%)	⬇️
src/dialog/props.ts	70.00% <0.00%> (-30.00%)	⬇️
src/calendar/props.ts	70.00% <0.00%> (-30.00%)	⬇️
src/popup/props.ts	75.00% <0.00%> (-25.00%)	⬇️
src/slider/props.ts	75.00% <0.00%> (-25.00%)	⬇️
src/message/props.ts	75.00% <0.00%> (-25.00%)	⬇️
src/tooltip/props.ts	75.00% <0.00%> (-25.00%)	⬇️
src/pagination/props.ts	75.00% <0.00%> (-25.00%)	⬇️
src/steps/step-item-props.ts	75.00% <0.00%> (-25.00%)	⬇️
... and 136 more

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