**Describe the bug**
ClickHouse doesn't return affected rows via MySQL protocol for INSERT queries after 20.5+

**How to reproduce**
i create clear docker-compose environment for reproduce behavior MySQL + clickhouse + php + python
https://gist.github.com/Slach/aa67440ce856a3a53f64f92eeddfbc1b

**Queries to run that lead to unexpected result**
```
INSERT INTO default.t1(n) SELECT * FROM numbers(1000)
```

**Expected behavior**
MySQL protocol shall return affected rows field for INSERT queries (it works successful in 20.3 and 20.4)
![image](https://user-images.githubusercontent.com/105560/97867431-aa22ae00-1d2f-11eb-8caf-05431ffd29b3.png)

**Actual behavior**
![image](https://user-images.githubusercontent.com/105560/97867401-9f681900-1d2f-11eb-93cc-5ae6f1f5981b.png)
: MySQLHandler(server_, socket_, ssl_enabled, connection_id_)
    , public_key(public_key_)
    , private_key(private_key_)
{}
void MySQLHandlerSSL::authPluginSSL()
{
    auth_plugin = std::make_unique<MySQLProtocol::Authentication::Sha256Password>(public_key, private_key, log);
}
void MySQLHandlerSSL::finishHandshakeSSL(
    size_t packet_size, char *buf, size_t pos, std::function<void(size_t)> read_bytes,
    MySQLProtocol::ConnectionPhase::HandshakeResponse & packet)
{
    read_bytes(packet_size); 
    SSLRequest ssl_request;
    ReadBufferFromMemory payload(buf, pos);
    payload.ignore(PACKET_HEADER_SIZE);
    ssl_request.readPayloadWithUnpacked(payload);
    connection_context.mysql.client_capabilities = ssl_request.capability_flags;
    connection_context.mysql.max_packet_size = ssl_request.max_packet_size ? ssl_request.max_packet_size : MAX_PACKET_LENGTH;
    secure_connection = true;
    ss = std::make_shared<SecureStreamSocket>(SecureStreamSocket::attach(socket(), SSLManager::instance().defaultServerContext()));
    in = std::make_shared<ReadBufferFromPocoSocket>(*ss);
    out = std::make_shared<WriteBufferFromPocoSocket>(*ss);
    connection_context.mysql.sequence_id = 2;
    packet_endpoint = std::make_shared<PacketEndpoint>(*in, *out, connection_context.mysql.sequence_id);
    packet_endpoint->receivePacket(packet); 
}
#endif
static bool isFederatedServerSetupSetCommand(const String & query)