Removed fancy showLogoutURL()

[marknl]

When running Racktables in a docker container, behind a nginx reversed proxy. The logout URL doesn't work. This is because there is no "server_name" available. This fixes that issue. Also, there's no need to generate such a "fancy" logout URL.

[infrastation]

Thank you for reporting this problem. This change will likely not work, as far as it is possible to tell from the diff, could you double-check please?

If $_SERVER['SERVER_NAME'] is not defined in this context, perhaps something else could be used instead?

[marknl]

Why wouldn't it work? I'm currently running a Racktables docker container with nginx reversed proxy in front of it including this change. It works fine.

[sknolin]

Somewhat related -I'd like to modify the logout url to support OIDC logout. Using apache mod_auth_oidc works fine for login, but a custom logout url is needed. So maybe instead making this configurable is more generally useful?

[marknl]

Also, the way I did it will have the browser automatically add the current "server_name". No need to provide that through a php variable. I like the idea of @sknolin to make it completely configurable.