[Bug Report] el-table 固定列和表头后添加多选会导致横向滚动条消失 #23053
Description
Element UI version
2.15.14
OS/Browsers version
操作系统：macOS12.6.7;谷歌浏览器：版本 134.0.6998.89（正式版本） (x86_64)
Vue version
2.7.16
Reproduction Link
https://codepen.io/wanggenqiang/pen/gbOdyEd
Steps to reproduce
el-table 固定列和表头后添加多选会导致横向滚动条消失
What is Expected?
让横向滚动条出来
What is actually happening?
让横向滚动条出来