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

 a follow up of https://github.com/apache/spark/pull/2377 and https://github.com/apache/spark/pull/2352, see detail there.

Author: wangfei <wangfei1@huawei.com>

Closes #2505 from scwf/patch-6 and squashes the following commits:

4874ec8 [wangfei] removes the evil MINOR HACK

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

@@ -28,8 +28,6 @@ import scala.collection.JavaConversions._
  * A set of test cases that validate partition and column pruning.
  */
 class PruningSuite extends HiveComparisonTest with BeforeAndAfter {
-  // MINOR HACK: You must run a query before calling reset the first time.
-  TestHive.sql("SHOW TABLES")
   TestHive.cacheTables = false
 
   // Column/partition pruning is not implemented for `InMemoryColumnarTableScan` yet, need to reset