Convert sort to partial_sort when the table is unbounded

### Is your feature request related to a problem or challenge?

in `fn replace_with_partial_sort`, there is a check
```rust
if !child.execution_mode().is_unbounded() {
return Ok(plan);
}
```
Isn't it better to have partial sorts even if the source is bounded?

### Describe the solution you'd like

Remove this check and always convert sorts to partial sorts if the requirements and properties allow

### Describe alternatives you've considered

_No response_

### Additional context

I guess it would heavily depend on the way how the data is ordered, and what is the rest of the plan, but a few benchmark results perhaps will make it more clear

Start by reading fn replace_with_partial_sort and the surrounding optimizer logic, focusing on the execution-mode check and the requirements and properties it already validates. Compare bounded and unbounded plans, then use or add benchmark coverage to determine when partial_sort is beneficial; done means the conversion is correct for eligible bounded inputs and supported by clear benchmark results.

Written by the indexing model from the issue text.