1057652: No longer delete derived products on import

**NOTE: Still not able to get a proper dev environment
set up, so this is missing tests and comes with the
possibility of breaking other tests.**

Must include all derived marketing/engineering products
when determining the marketing/engineering product
mapping during manifest import, else katello thinks
that they should be deleted after an import.

Derived products are used to create a sub pool once
the subscription is attached. We can not delete them.