[bug report] message box pop-up window, why do you focus the button as soon as you open it? As a result, the pop-up button is the focus style, with a layer of mask effect. Why does the message box pop focus the button when it opens? The resulting popover button is focused with a mask effect. It doesn't look good

### Element UI version
2.15.6

### OS/Browsers version
mac，Google Chrome 版本 95.0.4638.69（正式版本） (x86_64)

### Vue version
2.6.14

### Reproduction Link
https://codepen.io/347830076/pen/OJjoYgQ

### Steps to reproduce
直接点击重现链接的按钮，就可以看到，弹窗一打开，弹窗的按钮就立马聚焦，有了聚焦样式，聚焦效果是颜色变浅色了，我都没要点击，就变聚焦，这样不好

If I click on the button to reproduce the link, you can see that as soon as the popover opens, the popover button will immediately focus, and with the focus style, the focus effect will be lighter, so I don't even have to click on it, so IT's not good

### What is Expected?
弹窗一打开，弹窗的按钮不要聚焦

When the popover opens, the popover button should not be focused

### What is actually happening?
弹窗一打开，弹窗的按钮就立马聚焦，有了聚焦样式。

As soon as the popover opens, the popover button will immediately focus, with a focus style.