[bug report] select enable multiple filterable, click options, and the options will be reset to all. We hope that the filtered results can also be multiple selected

### Element UI version
2.13.0

### OS/Browsers version
--

### Vue version
3.0.0-alpha.2

### Reproduction Link
https://codepen.io/Swarz/pen/RwNexjM

### Steps to reproduce
0 总共5个选项
1 输入鸭，出现三个选择
2 点击其中一个选择，选项重置为5个

### What is Expected?
希望点击后依然是三个选项，通过删除输入来重置选项

### What is actually happening?
点击其中一个选择，选项重置为5个