[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

No files or tests are named in the issue. Start by locating the client-v2 settings and existing examples or tests for async_insert and socket_timeout, then compare their behavior with current ClickHouse server defaults. Done means the expected settings are documented, examples are updated, and test verification covers the intended behavior.

Written by the indexing model from the issue text.