**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.

{
    std::lock_guard lock(shared->storage_policies_mutex);
    return getDiskSelector(lock)->getDisksMap();
}
StoragePoliciesMap Context::getPoliciesMap() const
{
    std::lock_guard lock(shared->storage_policies_mutex);
    return getStoragePolicySelector(lock)->getPoliciesMap();
}
DiskSelectorPtr Context::getDiskSelector(std::lock_guard<std::mutex> & ) const
{
    if (!shared->merge_tree_disk_selector)
    {
        constexpr auto config_name = "storage_configuration.disks";
        const auto & config = getConfigRef();
        shared->merge_tree_disk_selector = std::make_shared<DiskSelector>(config, config_name, shared_from_this());
    }
    return shared->merge_tree_disk_selector;
}
StoragePolicySelectorPtr Context::getStoragePolicySelector(std::lock_guard<std::mutex> & lock) const
{
    if (!shared->merge_tree_storage_policy_selector)
    {
        constexpr auto config_name = "storage_configuration.policies";
        const auto & config = getConfigRef();
        shared->merge_tree_storage_policy_selector = std::make_shared<StoragePolicySelector>(config, config_name, getDiskSelector(lock));
    }
    return shared->merge_tree_storage_policy_selector;
}
void Context::updateStorageConfiguration(const Poco::Util::AbstractConfiguration & config)