csharp/src/Drivers/Apache: data types should be returned as-is instead of being converted

### What happened?

I expect structured types and intervals to be returned as their Arrow representation instead of being converted to string.

### How can we reproduce the bug?

_No response_

### Environment/Setup

_No response_

Start by inspecting csharp/src/Drivers/Apache and locate where structured types and intervals are converted before being returned. No reproduction steps or tests are provided; done means confirming those values are returned in their Arrow representation rather than as strings.

Written by the indexing model from the issue text.