**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.

alter_entry.emplace();
        mutation_znode.reset();
        auto current_metadata = getInMemoryMetadataPtr();
        StorageInMemoryMetadata future_metadata = *current_metadata;
        commands.apply(future_metadata, query_context);
        ReplicatedMergeTreeTableMetadata future_metadata_in_zk(*this, current_metadata);
        if (ast_to_str(future_metadata.sorting_key.definition_ast) != ast_to_str(current_metadata->sorting_key.definition_ast))
        {
            
            
            
            
            future_metadata_in_zk.sorting_key = serializeAST(*extractKeyExpressionList(future_metadata.sorting_key.definition_ast));
        }
        if (ast_to_str(future_metadata.sampling_key.definition_ast) != ast_to_str(current_metadata->sampling_key.definition_ast))
            future_metadata_in_zk.sampling_expression = serializeAST(*extractKeyExpressionList(future_metadata.sampling_key.definition_ast));
        if (ast_to_str(future_metadata.partition_key.definition_ast) != ast_to_str(current_metadata->partition_key.definition_ast))
            future_metadata_in_zk.partition_key = serializeAST(*extractKeyExpressionList(future_metadata.partition_key.definition_ast));
        if (ast_to_str(future_metadata.table_ttl.definition_ast) != ast_to_str(current_metadata->table_ttl.definition_ast))
        {
            if (future_metadata.table_ttl.definition_ast)
                future_metadata_in_zk.ttl_table = serializeAST(*future_metadata.table_ttl.definition_ast);
            else 
                future_metadata_in_zk.ttl_table = "";
        }
        String new_indices_str = future_metadata.secondary_indices.toString();
        if (new_indices_str != current_metadata->secondary_indices.toString())
            future_metadata_in_zk.skip_indices = new_indices_str;
        String new_projections_str = future_metadata.projections.toString();