[Improve][SDK] Make batch done idempotent in the DataProxy Go SDK

### Description

In the Dataproxy Go SDK, batchReq.done() may be invoked more than once for the same batch, resulting in callbacks being called twice and resources being released multiple times.

### InLong Component

InLong SDK

### Are you willing to submit PR?

- [x] Yes, I am willing to submit a PR!

### Code of Conduct

- [x] I agree to follow this project's [Code of Conduct](https://www.apache.org/foundation/policies/conduct)

Locate batchReq.done() in the DataProxy Go SDK and trace its callback and resource-release paths, first checking existing batch-related tests. Reproduce or add coverage for repeated done calls, then verify callbacks and cleanup occur only once and the SDK tests pass.

Written by the indexing model from the issue text.