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 (merged).

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 (closed), #13179 (closed), #13259 (closed), #13959 (closed)