Fix distributed sort parallelism for single node execution

[arhimondr]

Description

The AddExchanges optimizer rule is disabled for single node execution. The AddExchanges was responsible for marking the SortNode as partial. When the SortNode is not marked as partial, Velox only runs a single instance of a pipeline containing a SortNode.

Motivation and Context

Improve parallelism for queries running in single node mode containing ORDER BY

Impact

Improved performance for ORDER BY queries running in single node mode

Test Plan

Integration test

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Release Notes

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== RELEASE NOTES ==

General Changes
* Improve performance of ORDER BY queries on single node execution :pr:`25022`