Address a comment and add few more words in comments

Author: HyukjinKwon

python/pyspark/sql/tests.py

@@ -3073,7 +3073,7 @@ def test_sparksession_with_stopped_sparkcontext(self):
 
 class QueryExecutionListenerTests(unittest.TestCase, SQLTestUtils):
     # These tests are separate because it uses 'spark.sql.queryExecutionListeners' which is
-    # static and immutable. This can't be set or unset.
+    # static and immutable. This can't be set or unset, for example, via `spark.conf`.
 
     @classmethod
     def setUpClass(cls):

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

@@ -24,7 +24,7 @@ import org.apache.spark.sql.execution.QueryExecution
 import org.apache.spark.sql.util.QueryExecutionListener
 
 
-class TestQueryExecutionListener extends QueryExecutionListener with Logging {
+class TestQueryExecutionListener extends QueryExecutionListener {
   override def onSuccess(funcName: String, qe: QueryExecution, durationNs: Long): Unit = {
     OnSuccessCall.isOnSuccessCalled.set(true)
   }