**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.

return true;
    }
    catch (...)
    {
        return false;
    }
}
UInt32 Context::getZooKeeperSessionUptime() const
{
    std::lock_guard lock(shared->zookeeper_mutex);
    if (!shared->zookeeper || shared->zookeeper->expired())
        return 0;
    return shared->zookeeper->getSessionUptime();
}
void Context::setSystemZooKeeperLogAfterInitializationIfNeeded()
{
    
    
    
    
    
    std::lock_guard lock(shared->zookeeper_mutex);
    if (!shared->system_logs || !shared->system_logs->zookeeper_log)
        return;
    if (shared->zookeeper)
        shared->zookeeper->setZooKeeperLog(shared->system_logs->zookeeper_log);
    for (auto & zk : shared->auxiliary_zookeepers)
        zk.second->setZooKeeperLog(shared->system_logs->zookeeper_log);
}
void Context::initializeKeeperDispatcher([[maybe_unused]] bool start_async) const