[Bug Report] el-select 多选tag 点击清空按钮，tags样式错位

### Element UI version
2.15.7

### OS/Browsers version
macOS Big Sur 11.6.1

### Vue version
2.6.14

### Reproduction Link
https://codepen.io/Heyilin-603/pen/mdLbzzR

### Steps to reproduce
选中多个tag，再点击清空，tags会回闪错位一下再清空，tags越多越明显

### What is Expected?
点击清空后tags直接消失

### What is actually happening?
点击清空，选中的tags会回闪错位再消失