**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.

const MutationCommands & commands, ContextPtr query_context, const zkutil::ZooKeeperPtr & zookeeper) const
{
    const std::set<String> mutation_affected_partition_ids = getPartitionIdsAffectedByCommands(commands, query_context);
    if (mutation_affected_partition_ids.size() == 1)
    {
        const auto & affected_partition_id = *mutation_affected_partition_ids.cbegin();
        auto block_number_holder = allocateBlockNumber(affected_partition_id, zookeeper);
        if (!block_number_holder.has_value())
            return {};
        auto block_number = block_number_holder->getNumber();  
        return {{{affected_partition_id, block_number}}, std::move(block_number_holder)};
    }
    else
    {
        
        EphemeralLocksInAllPartitions lock_holder(
            fs::path(zookeeper_path) / "block_numbers", "block-", fs::path(zookeeper_path) / "temp", *zookeeper);
        PartitionBlockNumbersHolder::BlockNumbersType block_numbers;
        for (const auto & lock : lock_holder.getLocks())
        {
            if (mutation_affected_partition_ids.empty() || mutation_affected_partition_ids.count(lock.partition_id))
                block_numbers[lock.partition_id] = lock.number;
        }
        return {std::move(block_numbers), std::move(lock_holder)};
    }
}
void StorageReplicatedMergeTree::alter(