**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.

if (new_projections_str != current_metadata->projections.toString())
            future_metadata_in_zk.projections = new_projections_str;
        String new_constraints_str = future_metadata.constraints.toString();
        if (new_constraints_str != current_metadata->constraints.toString())
            future_metadata_in_zk.constraints = new_constraints_str;
        Coordination::Requests ops;
        size_t alter_path_idx = std::numeric_limits<size_t>::max();
        size_t mutation_path_idx = std::numeric_limits<size_t>::max();
        String new_metadata_str = future_metadata_in_zk.toString();
        ops.emplace_back(zkutil::makeSetRequest(fs::path(zookeeper_path) / "metadata", new_metadata_str, metadata_version));
        String new_columns_str = future_metadata.columns.toString();
        ops.emplace_back(zkutil::makeSetRequest(fs::path(zookeeper_path) / "columns", new_columns_str, -1));
        if (ast_to_str(current_metadata->settings_changes) != ast_to_str(future_metadata.settings_changes))
        {
            
            StorageInMemoryMetadata metadata_copy = *current_metadata;
            metadata_copy.settings_changes = future_metadata.settings_changes;
            changeSettings(metadata_copy.settings_changes, table_lock_holder);
            DatabaseCatalog::instance().getDatabase(table_id.database_name)->alterTable(query_context, table_id, metadata_copy);
        }
        
        
        int new_metadata_version = metadata_version + 1;
        alter_entry->type = LogEntry::ALTER_METADATA;
        alter_entry->source_replica = replica_name;
        alter_entry->metadata_str = new_metadata_str;
        alter_entry->columns_str = new_columns_str;
        alter_entry->alter_version = new_metadata_version;
        alter_entry->create_time = time(nullptr);
        auto maybe_mutation_commands = commands.getMutationCommands(