[SPARK-38959][SQL][FOLLOW-UP] Address feedback for RowLevelOperationR…

…untimeGroupFiltering

### What changes were proposed in this pull request?

This PR is to address the feedback on PR #36304 after that change was merged.

### Why are the changes needed?

These changes are needed for better code quality.

### Does this PR introduce _any_ user-facing change?

No.

### How was this patch tested?

Existing tests.

Closes #38526 from aokolnychyi/spark-38959-follow-up.

Authored-by: aokolnychyi <aokolnychyi@apple.com>
Signed-off-by: Wenchen Fan <wenchen@databricks.com>

sql/core/src/main/scala/org/apache/spark/sql/execution/dynamicpruning/RowLevelOperationRuntimeGroupFiltering.scala

@@ -78,9 +78,8 @@ case class RowLevelOperationRuntimeGroupFiltering(optimizeSubqueries: Rule[Logic
     // clone the relation and assign new expr IDs to avoid conflicts
     matchingRowsPlan transformUpWithNewOutput {
       case r: DataSourceV2Relation if r eq relation =>
-        val oldOutput = r.output
-        val newOutput = oldOutput.map(_.newInstance())
-        r.copy(output = newOutput) -> oldOutput.zip(newOutput)
+        val newRelation = r.newInstance()
+        newRelation -> r.output.zip(newRelation.output)
     }
   }