[client-v2] Insert/timeout settings

### Description

There are many issues with settings like `async_insert`, `socket_timeout`.
Mainly this is because default value was changes on server side and now behavior doesn't match expectations.

What should be done:
- Documentation and examples
- Test verification

Issue 中没有指定文件或测试。首先定位 client-v2 设置，以及 async_insert 和 socket_timeout 的现有示例或测试，然后将它们的行为与当前 ClickHouse 服务器默认值进行比较。当预期设置已完成文档记录、示例已更新，并且测试验证覆盖预期行为时，即视为完成。

由索引模型根据 Issue 内容生成。