ldap_blocked shouldn't apply when user not signing in with ldap credentials
Customer in internal link experienced an issue with a cloud provider ldap service which caused all their GitLab users to become ldap_blocked.
The customer's user base does not use ldap for authentication, they only use ldap for group memberships. During this outage the users could still authenticate using their normal authentication route, but they were prevented from signing in to GitLab because they were marked as ldap_blocked.
We have a separate issue around ldap users being removed from group memberships with ldap failures: #6054 but that's not what this customer was experiencing, or at least it wasn't the presenting complaint and didn't come in to the debugging work we did.
It doesn't seem logical to prevent a user from logging in at all when the credentials they are using to log in are complately separate from ldap. Maybe they might lose group memberships, which may make the ability to log in meaningless, but maybe not. I'm not sure how we might do it, but perhaps ldap_blocked should only apply when the auth method is actually ldap?