Migrate LDAP health checker to use permanent OpenLDAP & AD servers

At this point we have 4 LDAP servers up and running:

1. The OpenLDAP server that was running for a long time
2. New permanent ActiveDirectory server I brought in for testing
3. Temporary replicated OpenLDAP servers to test partial unavailability

We will not maintain all 4 servers, let the replicated servers expire at March 15 and migrate tests to use only the permanent servers.