Add call to getUsingItems() in all TestFoo.test_delete() methods

[Nicklas Nordborg]

I think the getUsingItems() method is never called otherwise during regular testing and there are a lot of non-trivial queries in there. NOTE! All test cases should delete only items which has no other items using it, so it is expected that the method call always return an empty list.

[Nicklas Nordborg]

Something like this should be enough:

dc.deleteItem(item);
Set<ItemProxy> using = item.getUsingItems();
if (using.size() > 0) 
{
   throw new BaseException(item + " is used by " + using);
}
dc.commit();

The call to dc.deleteItem() and dc.commit() is already in the code.

[Nicklas Nordborg]

(In [5340]) Fixes #1486: Add call to getUsingItems() in all TestFoo?.test_delete() methods