[Bug Report] When the DateTimePicker component sets both the format and value-format properties at the same time, the time selector will malfunction

### Element UI version
2.15.13

### OS/Browsers version
Edge 119.

### Vue version
2.6.11

### Reproduction Link
https://codepen.io/caojing/pen/rNPRBpm

### Steps to reproduce
1. Use the DatePicker component
2. Set the type attribute to datetimerange
3. Set the format attribute to yyyy-MM-dd
4. Set the value-format attribute to yyy-MM-dd HH:mm:ss
5. Open the selector panel for selection, the time selector will display abnormally (① It should display hours, minutes, and seconds, but it displays as year, month, and day ② After clicking, you can only select hours and minutes, but you cannot select seconds)

### What is Expected?
The time selector should normally display hours, minutes, and seconds, and you should be able to select them correctly after clicking；

### What is actually happening?
It does not display hours, minutes, and seconds, and you cannot select seconds after clicking；