[fix](case) drop table if exists before create it (#40205)

## Proposed changes

Issue Number: close #xxx

<!--Describe your changes.-->

regression-test/suites/show_p0/test_show_data_skew.groovy

@@ -16,6 +16,7 @@
 // under the License.
 
 suite("test_show_data_skew") {
+    sql """ DROP TABLE IF EXISTS test_show_data_skew; """
     sql """
         CREATE TABLE test_show_data_skew (
             id int,