Backport #25312 by @wxiaoguang
We only needs 2 lines to hide the dividers.
```
$dropdownLabelFilter.dropdown('setting', {'hideDividers': 'empty'});
$dropdownLabelFilter.dropdown('refreshItems');
```
Other code blocks are refactored by the way.


Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>