Fix CAS server status check

[cedric-anne]

Checklist before requesting a review

• I have read the CONTRIBUTING document.
• I have performed a self-review of my code.

Description

The cas_host configuration corresponds to the CAS server hostname. It must be prefixed by https:// to build a valid URL.
It fixes #18346.

I cannot test against a real CAS server, so I cannot validate the rest of the status checking logic.

[trasher]

This seems OK, but we probably need to also prevent usage of protocol in configuration, no? Or at least check here if it's already present.

[cedric-anne]

This seems OK, but we probably need to also prevent usage of protocol in configuration, no? Or at least check here if it's already present.

We may indeed improve this part, but I have no time to do it right now.

Right now, the status check will not work when the configuration is already done and is correct. The proposed changes focus on fixing that.

[trasher]

Cannot test.

[cedric-anne]

In GLPI, the default cas_port value is 443 (the default HTTPS port). I added a commit to consider the presence of the :80 port in HTTP URLs and the :443 port in HTTPS URLs as safe.