Unblocks user when active_directory is disabled and it can be found

We implemented a specific block state to handle user blocking that originates from LDAP filtering rules / directory state in !2242.

That introduced a regression in LDAP authentication when Active Directory support was disabled. You could have a scenario where the user would not be temporarily found (like a filtering rule), that would mark the user as `ldap_blocked`, but will never unblock it automatically when that state changed.

Fixes #14253, #13179, #13259, #13959

See merge request !3550