Description

Hello. The dropdown for selecting sites in the pageadmin is empty. The tree context does not have key "sites" anymore.
But the template "admin/cms/page/tree/base.html" is trying to iterate over them {% for site in tree.sites %}

Steps to reproduce

1. Go to /admin/cms/pagecontent/
2. Click on the three dots next to the search

Expected behaviour

A list of sites

Actual behaviour

An empty list of sites

Additional information (CMS/Python/Django versions)

Django==5.1.2
django-cms==4.1.3