[Feature Request][Go SDK]: Issue 22900 Followup: Optimize short reads of iterators for Length Prefixed coders.

### What would you like to happen?

As a followup to #22900, there's an opportunity to optimize "short reads" for iterators that need to consume the required number of elements on Close before the next element can begin processing.

If the coder type is Length Prefixed (strings, []bytes, custom coders, rows etc), it's possible to have a "skip" decoder that simply consumes the next values bytes, and avoid allocation the type in the first place.

### Issue Priority

Priority: 3

### Issue Component

Component: sdk-go