**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_WARNING(log, "Metadata version ({}) on replica is not up to date with metadata ({}) on source replica {}",
                metadata_version, source_metadata_version, source_replica);
    String source_metadata;
    String source_columns;
    while (true)
    {
        Coordination::Stat metadata_stat;
        Coordination::Stat columns_stat;
        source_metadata = zookeeper->get(source_path + "/metadata", &metadata_stat);
        source_columns = zookeeper->get(source_path + "/columns", &columns_stat);
        Coordination::Requests ops;
        Coordination::Responses responses;
        ops.emplace_back(zkutil::makeCheckRequest(source_path + "/metadata", metadata_stat.version));
        ops.emplace_back(zkutil::makeCheckRequest(source_path + "/columns", columns_stat.version));
        Coordination::Error code = zookeeper->tryMulti(ops, responses);
        if (code == Coordination::Error::ZOK)
            break;
        else if (code == Coordination::Error::ZBADVERSION)
            LOG_WARNING(log, "Metadata of replica {} was changed", source_path);
        else
            zkutil::KeeperMultiException::check(code, ops, responses);
    }
    ReplicatedMergeTreeLogEntryData dummy_alter;
    dummy_alter.type = LogEntry::ALTER_METADATA;
    dummy_alter.source_replica = source_replica;