**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.

{
    try
    {
        
        if (checkZooKeeperConfigIsLocal(getConfigRef(), "zookeeper"))
        {
            LOG_DEBUG(shared->log, "Keeper server is participant of the main zookeeper cluster, will try to connect to it");
            getZooKeeper();
            
            return true;
        }
        else
        {
            Poco::Util::AbstractConfiguration::Keys keys;
            getConfigRef().keys("auxiliary_zookeepers", keys);
            
            for (const auto & aux_zk_name : keys)
            {
                if (checkZooKeeperConfigIsLocal(getConfigRef(), "auxiliary_zookeepers." + aux_zk_name))
                {
                    LOG_DEBUG(shared->log, "Our Keeper server is participant of the auxiliary zookeeper cluster ({}), will try to connect to it", aux_zk_name);
                    getAuxiliaryZooKeeper(aux_zk_name);
                    
                    return true;
                }
            }
        }