Admin can not delete users, the form is not submitted when clicking "yes"

[wxiaoguang]

It seems a regression bug of #18064

• Add option to purge users #18064

In #18064, the "Delete" button was changed from <div class="ui red button delete-button" to <div class="ui red button show-modal" , however, the .show-modal event handler seems not handling the form submit correctly.

IMO, the .delete-button event handler could handle the form submit, not sure why the CSS class is changed.