Fix login in anonymous configuration with Shibboleth broken by NXP-22326

• Starting from a customer-given Shibboleth anonymous configuration, which works until 7.10-HF27:
• Adapt and install the attached project to a Shibboleth configuration.
• Enter a URL such as https://sp.shibboleth.com/nuxeo/site/esupversions/61a27353-eb21-4e4f-a48c-967de003583f and enter a user login jdoe/jdospass or Administrator/Administrator, and when logged in as Administrator, go to the "Admin" tab.
• nuxeoctl stop
• nuxeoctl mp-install nuxeo-7.10-HF28
• nuxeoctl start
• Enter a URL such as https://sp.shibboleth.com/nuxeo/site/esupversions/61a27353-eb21-4e4f-a48c-967de003583f and enter a user login jdoe/jdospass or Administrator/Administrator, and when logged in as Administrator, go to the "Admin" tab...
• You are now watching the issue: there is no "Admin" tab, and the choice in the "Administrator" menu is to connect, not to disconnect...

The NXP-22326, fixed in Nuxeo 7.10 HF28 is the likely culprit of the issue.