OPENDJ-3066 LDAPReplicationDomain should track import and export of the domain via ReplicationDomain

When a domain is initialized by protocol, ReplicationDomain would initiate an import and restart the broker after it is finished. It considers the import finished when the broker has started.
On the other hand LDAPDomainProtocol may write the server state after import has finished but the broker is still in the process of being restarted,
leading to a race condition between the configuration handler and the state of import.
Always use the same check for deciding wheteher import/export has completed.