**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.

{
    
    shared->max_partition_size_to_drop.store(max_size, std::memory_order_relaxed);
}
void Context::checkPartitionCanBeDropped(const String & database, const String & table, const size_t & partition_size) const
{
    size_t max_partition_size_to_drop = shared->max_partition_size_to_drop.load(std::memory_order_relaxed);
    checkCanBeDropped(database, table, partition_size, max_partition_size_to_drop);
}
InputFormatPtr Context::getInputFormat(const String & name, ReadBuffer & buf, const Block & sample, UInt64 max_block_size, const std::optional<FormatSettings> & format_settings) const
{
    return FormatFactory::instance().getInput(name, buf, sample, shared_from_this(), max_block_size, format_settings);
}
OutputFormatPtr Context::getOutputFormat(const String & name, WriteBuffer & buf, const Block & sample) const
{
    return FormatFactory::instance().getOutputFormat(name, buf, sample, shared_from_this());
}
OutputFormatPtr Context::getOutputFormatParallelIfPossible(const String & name, WriteBuffer & buf, const Block & sample) const
{
    return FormatFactory::instance().getOutputFormatParallelIfPossible(name, buf, sample, shared_from_this());
}
time_t Context::getUptimeSeconds() const
{
    auto lock = getLock();
    return shared->uptime_watch.elapsedSeconds();
}
void Context::setConfigReloadCallback(ConfigReloadCallback && callback)