Enrich tests for foreign key with PREPARE and "Non-Transactional DML"

[YangKeao]

Enhancement

We haven't tested the foreign key check with PREPARE and "Non-Transactional DML". We need to check the following things:

1. When the foreign key check failed, what will happen for the "Non-Transactional DML".
2. When the foreign key is added, the prepared plan cache should be invalidated.

They should work fine, as the "Non-Transactional DML" will just finish (though part of the DML may success), and the plan cache will always be invalidated if the schema version increased.

[YangKeao]

Maybe we should also consider the situation when the DDL is in a middle-stage.