Enable SPARK-57298 collect_set tests when Spark 4.2 SQL diff lands

## Background

PR #5166 fixes #4966 and adds Comet SQL-file coverage for Spark 4.2 `collect_set` normalization.

The repository currently has no `dev/diffs/4.2*.diff` and no Spark 4.2 Spark SQL Tests job, so the corresponding upstream Spark tests cannot yet be enabled in the Comet diff.

## Task

Once a Spark 4.2 diff and CI job are added, enable these `DataFrameAggregateSuite` tests:

- `SPARK-57298: collect_set normalizes NaN and -0.0 for floating-point types`
- `SPARK-57298: collect_set normalizes NaN and -0.0 nested in complex types`

Verify both tests pass with native `collect_set`.

Related: #4966, #5166, and [review 4830920688](https://github.com/apache/datafusion-comet/pull/5166#pullrequestreview-4830920688).