**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);
    if (shared->merge_tree_disk_selector)
        shared->merge_tree_disk_selector
            = shared->merge_tree_disk_selector->updateFromConfig(config, "storage_configuration.disks", shared_from_this());
    if (shared->merge_tree_storage_policy_selector)
    {
        try
        {
            shared->merge_tree_storage_policy_selector = shared->merge_tree_storage_policy_selector->updateFromConfig(
                config, "storage_configuration.policies", shared->merge_tree_disk_selector);
        }
        catch (Exception & e)
        {
            LOG_ERROR(
                shared->log, "An error has occurred while reloading storage policies, storage policies were not applied: {}", e.message());
        }
    }
    if (shared->storage_s3_settings)
    {
        shared->storage_s3_settings->loadFromConfig("s3", config);
    }
}
const MergeTreeSettings & Context::getMergeTreeSettings() const