[Bug Report] el-popover悬浮框在el-table表格单元格内的输入框中使用时的异常问题

### Element UI version
2.15.14

### OS/Browsers version
Windows11

### Vue version
2.7.16

### Reproduction Link
https://elementui.github.io/issue-generator

### Steps to reproduce
HTML部分：
```

...






{{item.optionName}}








{{scope.row.purchaseManufacturer}}



...

```
JS部分：
```
onRadioGroupChangeForPurchaseManufacturer: function (value, rowIndex) {
console.info('onRadioGroupChangeForPurchaseManufacturer value----->', value, rowIndex);
// 关闭当前popover悬浮框
vm.$refs['popover_purchase_manufacturer_' + rowIndex].doClose();
},
onInputFocusForPurchaseManufacturer: function (event, rowIndex) {
console.info('onInputFocusForPurchaseManufacturer rowIndex----->', rowIndex);
vm.manufacturerOptions = vm.manufacturerOptionsCopy.slice(0, vm.manufacturerOptionsRange);
},
onInputValueChangeForPurchaseManufacturer: function (value, rowIndex) {
console.info('onInputValueChangeForPurchaseManufacturer rowIndex----->', rowIndex);
let search = value;
if (search) {
let waitRenderOptions = vm.manufacturerOptionsCopy.filter((item, i) => {
return item.optionName.indexOf(search) != -1
|| item.pinyinShortCode.indexOf(search) != -1 || item.pinyinFullCode.indexOf(search) != -1;
});
vm.manufacturerOptions = waitRenderOptions.slice(0, vm.manufacturerOptionsRange);
} else {
vm.manufacturerOptions = vm.manufacturerOptionsCopy.slice(0, vm.manufacturerOptionsRange);
}
},
```
异常问题出在onRadioGroupChangeForPurchaseManufacturer事件中的el-popover实例的doClose方法，效果是单元格中的输入框绑定的el-popover悬浮框中的单选框组选完任意一个选项后自动隐藏el-popover悬浮框，正常情况下是有效的，但当el-table表格中随便一列设置为fixed固定列时，el-popover实例的doClose方法就失效了！

### What is Expected?
el-table表格中无论是否有fixed固定列存在，都不应该影响el-popover实例的doClose方法！

### What is actually happening?
el-table表格中随便一列设置为fixed固定列时，el-popover实例的doClose方法就失效了！