Batch Insert r2dbc

Looks like bulk inserts are inserting 1 by 1 and not in batches.

I have created the following table:

```
CREATE TABLE IF NOT EXISTS test
(
`a` Int16,
`b` Int16,
`created` DateTime
)
ENGINE = MergeTree()
PARTITION BY (toYYYYMM(created))
ORDER BY (created)
TTL created + INTERVAL 13 MONTH;
```

If I try to do the following:

```
public Mono saveAll(){
return Mono.from(connectionFactory.create())
.flatMapMany(conn -> execute(conn)).then();
}

private Publisher execute(Connection conn) {
return conn.createStatement("insert into test values (:a, :b, :created)")
.bind("a",1)
.bind("b", 2)
.bind("created", LocalDateTime.now())
.add()
.bind("a",5)
.bind("b", 6)
.bind("created", LocalDateTime.now())
.execute();
}
```
When checking the logs, I can see that 2 connections are established and inserts are run independently so it is not acting as a batch insert.

```
2024-09-02T10:43:28.253Z DEBUG 49005 --- [ckHouseWorker-1] com.clickhouse.client.AbstractClient : Connection established: com.clickhouse.client.http.HttpUrlConnectionImpl@1f010075
2024-09-02T10:43:28.253Z DEBUG 49005 --- [ckHouseWorker-1] c.c.client.http.ClickHouseHttpClient : Query: insert into `default`.test values (1, 2, 1725273808)
2024-09-02T10:43:28.254Z DEBUG 49005 --- [ckHouseWorker-2] com.clickhouse.client.AbstractClient : Connection established: com.clickhouse.client.http.HttpUrlConnectionImpl@35e8f1b6
2024-09-02T10:43:28.254Z DEBUG 49005 --- [ckHouseWorker-2] c.c.client.http.ClickHouseHttpClient : Query: insert into `default`.test values (5, 6, 1725273808)
```

Am I doing something wrong or is this the intended behaviour?

I have also tried using this approach but same behaviour

```
return conn.createBatch()
.add("insert into test values (1, 2, '2024-01-17 00:00:00')")
.add("insert into test values (5, 6, '2024-01-17 00:00:00')")
.execute();
```

I am using clickhouse-r2dbc version 0.6.4.

使用 clickhouse-r2dbc 0.6.4 重现该示例，从 issue 中展示的 Connection.createStatement(...).add() 和 Connection.createBatch() 入口点开始。将它们的行为与日志中记录的独立插入进行比较，并确定观察到的语义是否是预期的。完成的标准是明确 batch 行为，并通过适当的驱动程序更改或文档化的行为解决该 issue。

由索引模型根据 Issue 内容生成。