**Describe the issue**
ClickHouse is unable to start up after upgrading from 20.8 to 21.8. 

There is a replicated table with `:` in zk path and it couldn't be loaded with:

`2021.09.15 03:49:58.435071 [ 633075 ] {} <Error> Application: DB::Exception: Unknown auxiliary ZooKeeper name '/test_prefix'. If it's required it can be added to the section <auxiliary_zookeepers> in config.xml: Cannot attach table `db1`.`table1` from metadata file /var/lib/clickhouse/metadata/db1/table1.sql from query ATTACH TABLE db1.table1 (`field1` String, `date` Date) ENGINE = ReplicatedMergeTree('/test_prefix:db1/{shard}/table1', '{replica}') PARTITION BY toMonth(date) PRIMARY KEY field1 ORDER BY field1 SETTINGS index_granularity = 8192: while loading database `db1` from path /var/lib/clickhouse/metadata/db1
`

**Expected behavior**
ClickHouse server is able to startup after upgrade without schema change. "test_prefix" in "/test_prefix:db1/{shard}/table1" is not interpreted as an auxiliary ZooKeeper name.

LOG_TRACE(log, "Found zookeper active replicas for part {}: {}", part.name, active_replicas.size());
    if (active_replicas.empty())
        return best_replica;
    /** You must select the best (most relevant) replica.
    * This is a replica with the maximum `log_pointer`, then with the minimum `queue` size.
    * NOTE This is not exactly the best criteria. It does not make sense to download old partitions,
    *  and it would be nice to be able to choose the replica closest by network.
    * NOTE Of course, there are data races here. You can solve it by retrying.
    */
    Int64 max_log_pointer = -1;
    UInt64 min_queue_size = std::numeric_limits<UInt64>::max();
    for (const String & replica : active_replicas)
    {
        String current_replica_path = fs::path(zookeeper_path) / "replicas" / replica;
        String log_pointer_str = zookeeper->get(fs::path(current_replica_path) / "log_pointer");
        Int64 log_pointer = log_pointer_str.empty() ? 0 : parse<UInt64>(log_pointer_str);
        Coordination::Stat stat;
        zookeeper->get(fs::path(current_replica_path) / "queue", &stat);
        size_t queue_size = stat.numChildren;
        if (log_pointer > max_log_pointer
            || (log_pointer == max_log_pointer && queue_size < min_queue_size))
        {
            max_log_pointer = log_pointer;
            min_queue_size = queue_size;
            best_replica = replica;
        }
    }
    return best_replica;
}
String StorageReplicatedMergeTree::findReplicaHavingPart(