Clear temp tables after each suite

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/catalog/SessionCatalog.scala

@@ -277,6 +277,14 @@ class SessionCatalog(externalCatalog: ExternalCatalog, conf: CatalystConf) {
    */
   def refreshTable(name: TableIdentifier): Unit = { /* no-op */ }
 
+  /**
+   * Drop all existing temporary tables.
+   * For testing only.
+   */
+  def clearTempTables(): Unit = {
+    tempTables.clear()
+  }
+
   /**
    * Return a temporary table exactly as it was stored.
    * For testing only.

sql/hive/src/main/scala/org/apache/spark/sql/hive/test/TestHive.scala

@@ -478,6 +478,7 @@ class TestHiveContext private[hive](
 
       cacheManager.clearCache()
       loadedTables.clear()
+      sessionState.catalog.clearTempTables()
       sessionState.catalog.invalidateCache()
       metadataHive.reset()