**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.

RemoteHostFilter remote_host_filter; 
    std::optional<TraceCollector> trace_collector;        
    
    
    std::shared_ptr<Clusters> clusters;
    ConfigurationPtr clusters_config;                        
    mutable std::mutex clusters_mutex;                       
    std::shared_ptr<AsynchronousInsertQueue> async_insert_queue;
    std::map<String, UInt16> server_ports;
    bool shutdown_called = false;
    
    bool is_background_executors_initialized = false;
    Stopwatch uptime_watch;
    Context::ApplicationType application_type = Context::ApplicationType::SERVER;
    
    std::vector<std::unique_ptr<ShellCommand>> bridge_commands;
    Context::ConfigReloadCallback config_reload_callback;
    ContextSharedPart()
        : access_control_manager(std::make_unique<AccessControlManager>()), macros(std::make_unique<Macros>())
    {
        
        static std::atomic<size_t> num_calls{0};
        if (++num_calls > 1)
        {
            std::cerr << "Attempting to create multiple ContextShared instances. Stack trace:\n" << StackTrace().toString();
            std::cerr.flush();
            std::terminate();
        }
    }
    ~ContextSharedPart()