[FIX] website: allow to have all pages popups with a slide hover footer

Before this commit, the popup snippet was not displayed correctly if it
had to be displayed on all pages and the footer was a slide hover
footer. This commit just permits disabling the footer effect while the
popup is displayed.

Steps to reproduce the bug:
- Drop some block on a page
- Set the the footer Slideout Effect to "slide hover"
- Add a popup and set it to be displayed on all pages
- Save

=> The page is blocked when the popup appears.

opw-2971181

X-original-commit: bae2c6e9
Part-of: odoo/odoo#107062
Co-authored-by: Romain Derie <rde@odoo.com>
Co-authored-by: qsm-odoo <qsm@odoo.com>