[FIX] web: correctly close confirm dialog

Let's assume the following scenario:
 - have an action in target new (e.g. a form view)
 - in the dialog, have an action/object button with confirm
   attribute
 - when clicking on that button, a confirm dialog opens
 - if validated, the following action returned by the server
   is again an action in target new

Before this commit, the confirm dialog remained in the DOM.

This issue occurred because it's parent wasn't correctly set (wrong
use of `this`), so when the first dialog was destroyed, the confirm
dialog wasn't automatically destroyed in turn.

OPW~2440712

closes odoo/odoo#66340

X-original-commit: 2016fe31af970976775c9df160a31abfbec742ba
Signed-off-by: Jorge Pinna Puissant (jpp) <jpp@odoo.com>