[SPARK-23263][TEST] CTAS should update stat if autoUpdate statistics is enabled

## What changes were proposed in this pull request?
The [SPARK-27403](https://issues.apache.org/jira/browse/SPARK-27403) fixed CTAS cannot update statistics even if `spark.sql.statistics.size.autoUpdate.enabled` is enabled, as mentioned in [SPARK-23263](https://issues.apache.org/jira/browse/SPARK-23263).

This pr adds tests for that fix.

## How was this patch tested?

N/A

Closes apache#20430 from wangyum/SPARK-23263.

Authored-by: Yuming Wang <[email protected]>
Signed-off-by: HyukjinKwon <[email protected]>

Author: wangyum

sql/hive/src/test/scala/org/apache/spark/sql/hive/StatisticsSuite.scala

@@ -1431,4 +1431,26 @@ class StatisticsSuite extends StatisticsCollectionTestBase with TestHiveSingleto
       assert(catalogStats.rowCount.isEmpty)
     }
   }
+
+  test(s"CTAS should update statistics if ${SQLConf.AUTO_SIZE_UPDATE_ENABLED.key} is enabled") {
+    val tableName = "SPARK_23263"
+    Seq(false, true).foreach { isConverted =>
+      Seq(false, true).foreach { updateEnabled =>
+        withSQLConf(
+          SQLConf.AUTO_SIZE_UPDATE_ENABLED.key -> updateEnabled.toString,
+          HiveUtils.CONVERT_METASTORE_PARQUET.key -> isConverted.toString) {
+          withTable(tableName) {
+            sql(s"CREATE TABLE $tableName STORED AS parquet AS SELECT 'a', 'b'")
+            val catalogTable = getCatalogTable(tableName)
+            // Hive serde tables always update statistics by Hive metastore
+            if (!isConverted || updateEnabled) {
+              assert(catalogTable.stats.nonEmpty)
+            } else {
+              assert(catalogTable.stats.isEmpty)
+            }
+          }
+        }
+      }
+    }
+  }
 }