**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 AlterCommands & commands, ContextPtr query_context, AlterLockHolder & table_lock_holder)
{
    assertNotReadonly();
    auto table_id = getStorageID();
    if (commands.isSettingsAlter())
    {
        
        
        StorageInMemoryMetadata future_metadata = getInMemoryMetadata();
        commands.apply(future_metadata, query_context);
        merge_strategy_picker.refreshState();
        changeSettings(future_metadata.settings_changes, table_lock_holder);
        DatabaseCatalog::instance().getDatabase(table_id.database_name)->alterTable(query_context, table_id, future_metadata);
        return;
    }
    auto ast_to_str = [](ASTPtr query) -> String
    {
        if (!query)
            return "";
        return queryToString(query);
    };
    const auto zookeeper = getZooKeeper();
    std::optional<ReplicatedMergeTreeLogEntryData> alter_entry;
    std::optional<String> mutation_znode;
    while (true)
    {