Address review comment: add code comment

Author: karuppayya

sql/core/src/test/scala/org/apache/spark/sql/InjectRuntimeFilterSuite.scala

@@ -206,6 +206,8 @@ class InjectRuntimeFilterSuite extends QueryTest with SQLTestUtils with SharedSp
     sql("analyze table bf5part compute statistics for columns a5, b5, c5, d5, e5, f5")
     sql("analyze table bf5filtered compute statistics for columns a5, b5, c5, d5, e5, f5")
 
+    // Tests depend on intermediate results that would otherwise be cleaned up when
+    // shuffle clean up is enabled, causing test failures.
     conf.setConf(SQLConf.CLASSIC_SHUFFLE_DEPENDENCY_FILE_CLEANUP_ENABLED, false)
     // `MergeScalarSubqueries` can duplicate subqueries in the optimized plan and would make testing
     // complicated.

sql/core/src/test/scala/org/apache/spark/sql/execution/adaptive/AdaptiveQueryExecSuite.scala

@@ -69,6 +69,8 @@ class AdaptiveQueryExecSuite
 
   protected override def beforeAll(): Unit = {
     super.beforeAll()
+    // Tests depend on intermediate results that would otherwise be cleaned up when
+    // shuffle clean up is enabled, causing test failures.
     sqlConf.setConf(SQLConf.CLASSIC_SHUFFLE_DEPENDENCY_FILE_CLEANUP_ENABLED, false)
   }