Add test similar to GeneratedPropertySingleTableTest for the missing dbs

[DavideD]

GeneratedPropertySingleTableTest uses native sql queries, so we only tests some dbs.

Because the code executed might be quite different among databases, we should probably make sure that the test passes for the other databases as well.

In particular, Hibernate Reactive cannot enable the GetGeneratedKeys strategy the same way ORM sometimes does with JDBC.