Avoid CometColumnarExchange when next query stage requires CometColumnarToRow #2880

What is the problem the feature request solves?

The golden file at spark/src/test/resources/tpcds-plan-stability/approved-plans-v1_4-spark3_5/q1.native_datafusion/extended.txt has this section:

      :     :     :  +- HashAggregate
      :     :     :     +- CometColumnarToRow
      :     :     :        +- CometColumnarExchange
      :     :     :           +- HashAggregate

Presumably the first HashAggregate shown here is not supported by Comet (fallback reasons are missing for some reason) so this query stage needs to call CometColumnarToRow.

There is probably no benefit in using columnar shuffle in the child stage if the parent stage immediately converts back to row-based, although we should confirm that assumption.

Describe the potential solution

Additional context

No response