**Describe the solution you'd like**

We already can run clickhouse-server without configured ZooKeeper (the tables will start in read-only mode)
and with configured ZooKeeper, if it starts to be inaccessible at runtime (the tables will be read-only until the session is re-established).

Let's also make it possible to start up when ZooKeeper is unavailable.

**Additional context**

If that will be very hard to implement, we can consider other options:
- lazy attaching of the tables after sever start-up;
- a maintenance mode when the tables are not attached at start-up and require manual ATTACH queries.
}
            else
                throw Coordination::Exception(code, quorum_status_path);
        }
        else
        {
            LOG_TRACE(log, "Quorum {} still not satisfied (have only {} replicas), updating node",
                      quorum_status_path, quorum_entry.replicas.size());
            
            auto code = zookeeper->trySet(quorum_status_path, quorum_entry.toString(), stat.version);
            if (code == Coordination::Error::ZOK)
            {
                break;
            }
            else if (code == Coordination::Error::ZNONODE)
            {
                
                break;
            }
            else if (code == Coordination::Error::ZBADVERSION)
            {
                
                continue;
            }
            else
                throw Coordination::Exception(code, quorum_status_path);
        }
    }
}
void StorageReplicatedMergeTree::cleanLastPartNode(const String & partition_id)