Allow disabling the logout on provider side

That works for me. Renaming it to something like "Misleading 'Logout mechanism' field in the configuration object" and removing the field together with its getter and setter matches what is actually left of my report — and it can come back whenever someone implements it.

No separate issue from my side for now: I have no evidence of an EntraID-specific logout problem. The loop I ran into was caused by my own post-logout target, and the one thing I could not verify — whether the provider session was really terminated — is not something our environment can prove either way, since our clients are Entra-joined and a silent re-authentication through device SSO is expected there regardless. If I get a reproducible case with logs after our production rollout, I will open a dedicated issue rather than reviving this one.

Thanks for taking the time.