[bug report] the hook before upload of the upload component will trigger the on remove hook event after returning false

### Element UI version
2.15.6

### OS/Browsers version
window10/Google Chrome版本 79.0.3945.130（正式版本） （32 位）

### Vue version
2.6.12

### Reproduction Link
https://codepen.io/zbjy/pen/QWMaXqZ

### Steps to reproduce
随便上传一张图片，会触发弹窗输出1

### What is Expected?
上传前不触发on-remove钩子

### What is actually happening?
会出触发on-remove钩子