Spring Test helpfully rolls back any changes made to the database within a test method. This means that it is not necessary to take the time to delete/reload the test data
Spring Test and DbUnit is two excellent frameworks. But it doesn't make sense to combine them. Since Spring Test execute a rollback on the connection, it cleans up afterwards, while DbUnit cleans up and insert test data in the @Before method.
Use Spring if you're not dependent on any dynamic data and dbUnit otherwise.