**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.

}
        }
        PartLog::addNewParts(getContext(), res_parts, watch.elapsed());
    }
    catch (...)
    {
        PartLog::addNewParts(getContext(), res_parts, watch.elapsed(), ExecutionStatus::fromCurrentException());
        throw;
    }
    tryRemovePartsFromZooKeeperWithRetries(parts_to_remove);
    res_parts.clear();
    parts_to_remove.clear();
    cleanup_thread.wakeup();
    return true;
}
void StorageReplicatedMergeTree::executeClonePartFromShard(const LogEntry & entry)
{
    auto zookeeper = getZooKeeper();
    Strings replicas = zookeeper->getChildren(entry.source_shard + "/replicas");
    std::shuffle(replicas.begin(), replicas.end(), thread_local_rng);
    String replica;
    for (const String & candidate : replicas)
    {
        if (zookeeper->exists(entry.source_shard + "/replicas/" + candidate + "/is_active"))
        {
            replica = candidate;
            break;
        }
    }
    if (replica.empty())