**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.

LOG_TRACE(log, message);
        return handle_noop(message);
    };
    bool assigned = false;
    if (!partition && final)
    {
        DataPartsVector data_parts = getDataPartsVector();
        std::unordered_set<String> partition_ids;
        for (const DataPartPtr & part : data_parts)
            partition_ids.emplace(part->info.partition_id);
        for (const String & partition_id : partition_ids)
        {
            assigned = try_assign_merge(partition_id);
            if (!assigned)
                break;
        }
    }
    else
    {
        String partition_id;
        if (partition)
            partition_id = getPartitionIDFromQuery(partition, query_context);
        assigned = try_assign_merge(partition_id);
    }
    table_lock.reset();
    for (auto & merge_entry : merge_entries)
        waitForLogEntryToBeProcessedIfNecessary(merge_entry, query_context);
    return assigned;
}
bool StorageReplicatedMergeTree::executeMetadataAlter(const StorageReplicatedMergeTree::LogEntry & entry)