Remove unnecessary integration test

test/data/create_simple_decimal.sql

@@ -1,5 +0,0 @@
-create table customer (
-"CUST_ID" INTEGER not null,
-"USER_ID" DECIMAL(18,0) not null,
-primary key ("CUST_ID")
-);

test/data/insert_simple_decimal.sql

@@ -1 +0,0 @@
-insert into CUSTOMER (CUST_ID, USER_ID) values (1, 12345);