Legacy promotion removal: Removing environment_product model

Removing environment_product model since products are no longer being
promoted. Instead, now repos join environments and products directly.
Product: Fixing intermittent test failure

Fixing problem caused by shallow copy of SIMPLE_PRODUCT. It was altering the
value of SIMPLE_PRODUCT.
API tests: Fixing intermittent test failure
Merge pull request #2546 from daviddavis/delete-environment-product

Removing environment product