[Bug Report] <el-select> selected value is too long on Firefox

### Element UI version
2.15.14

### OS/Browsers version
firefox 131.0.3

### Vue version
2.7.16

### Reproduction Link
https://jsfiddle.net/j6Lexct8/10/

### Steps to reproduce
el-select fixed width, if the selected option is too long, the value selected by el-select will show the front part in Google Chrome, which is normal, and only the back part will be displayed on Firefox
choose a longer option on firefox

### What is Expected?
the value selected by el-select will show the front part in firefox

### What is actually happening?
the value selected by el-select showed the back part in firefox