**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 USE_NURAFT
    std::lock_guard lock(shared->keeper_dispatcher_mutex);
    if (!shared->keeper_dispatcher)
        return;
    shared->keeper_dispatcher->updateConfiguration(config);
#endif
}
zkutil::ZooKeeperPtr Context::getAuxiliaryZooKeeper(const String & name) const
{
    std::lock_guard lock(shared->auxiliary_zookeepers_mutex);
    auto zookeeper = shared->auxiliary_zookeepers.find(name);
    if (zookeeper == shared->auxiliary_zookeepers.end())
    {
        const auto & config = shared->auxiliary_zookeepers_config ? *shared->auxiliary_zookeepers_config : getConfigRef();
        if (!config.has("auxiliary_zookeepers." + name))
            throw Exception(
                ErrorCodes::BAD_ARGUMENTS,
                "Unknown auxiliary ZooKeeper name '{}'. If it's required it can be added to the section <auxiliary_zookeepers> in "
                "config.xml",
                name);
        zookeeper = shared->auxiliary_zookeepers.emplace(name,
                        std::make_shared<zkutil::ZooKeeper>(config, "auxiliary_zookeepers." + name, getZooKeeperLog())).first;
    }
    else if (zookeeper->second->expired())
        zookeeper->second = zookeeper->second->startNewSession();
    return zookeeper->second;
}
void Context::resetZooKeeper() const