**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.

if (part_path.empty())
            throw Exception(ErrorCodes::NO_REPLICA_HAS_PART, "Part {} does not exist on any replica", part_name);
        /** Let's check that there is no such part in the `detached` directory (where we will write the downloaded parts).
          * Unreliable (there is a race condition) - such a part may appear a little later.
          */
        if (checkIfDetachedPartExists(part_name))
            throw Exception(ErrorCodes::DUPLICATE_DATA_PART, "Detached part " + part_name + " already exists.");
        LOG_INFO(log, "Will fetch part {} from shard {} (zookeeper '{}')", part_name, from_, auxiliary_zookeeper_name);
        try
        {
            
            if (!fetchPart(part_name, metadata_snapshot, part_path, true, 0, zookeeper))
                throw Exception(ErrorCodes::UNFINISHED, "Failed to fetch part {} from {}", part_name, from_);
        }
        catch (const DB::Exception & e)
        {
            if (e.code() != ErrorCodes::RECEIVED_ERROR_FROM_REMOTE_IO_SERVER && e.code() != ErrorCodes::RECEIVED_ERROR_TOO_MANY_REQUESTS
                && e.code() != ErrorCodes::CANNOT_READ_ALL_DATA)
                throw;
            LOG_INFO(log, e.displayText());
        }
        return;
    }
    String partition_id = getPartitionIDFromQuery(partition, query_context);
    LOG_INFO(log, "Will fetch partition {} from shard {} (zookeeper '{}')", partition_id, from_, auxiliary_zookeeper_name);
    /** Let's check that there is no such partition in the `detached` directory (where we will write the downloaded parts).
      * Unreliable (there is a race condition) - such a partition may appear a little later.
      */
    if (checkIfDetachedPartitionExists(partition_id))
        throw Exception("Detached partition " + partition_id + " already exists.", ErrorCodes::PARTITION_ALREADY_EXISTS);