[Fix](regression) Fix typo in test_schema_change_unique_mow (#39196)

## Proposed changes

fix typo in #39173

regression-test/suites/schema_change_p0/test_schema_change_unique_mow.groovy

@@ -173,7 +173,7 @@ suite("test_schema_change_unique_mow", "p0") {
                 return true
             }
             cnt--;
-            int val = 100000 + max_try_num
+            int val = 100000 + cnt
             sql """ insert into ${tableName3} values (${val}, 2, 3, 4, 5, 6.6, 1.7, 8.8,
     'a', 'b', 'c', '2021-10-30', '2021-10-30 00:00:00', 9527) """
             return false