[SPARK-3481][SQL] Removes the evil MINOR HACK

This is a follow up of #2352. Now we can finally remove the evil "MINOR HACK", which covered up the eldest bug in the history of Spark SQL (see details [here](https://github.com/apache/spark/pull/2352#issuecomment-55440621)).

Author: Cheng Lian <lian.cs.zju@gmail.com>

Closes #2377 from liancheng/remove-evil-minor-hack and squashes the following commits:

0869c78 [Cheng Lian] Removes the evil MINOR HACK

sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/HiveComparisonTest.scala

@@ -250,9 +250,9 @@ abstract class HiveComparisonTest
       }
 
       try {
-        // MINOR HACK: You must run a query before calling reset the first time.
-        TestHive.sql("SHOW TABLES")
-        if (reset) { TestHive.reset() }
+        if (reset) {
+          TestHive.reset()
+        }
 
         val hiveCacheFiles = queryList.zipWithIndex.map {
           case (queryString, i)  =>