Since cd3add960e Spree soft-deletes products and as such the models not
destroyed but updated setting a value for the `deleted_at` field.
This turns what used to be deletes into updates thus triggering AR's
update callbacks instead of the destroy ones. As a result, this bypasses
the logic to refresh the products cache on destroy and hits the
`after_save` callback.
Furthermore, since act_as_paranoid (the soft-delete gem Spree uses) uses
a default scope to avoid retrieving soft-deleted records we need to
purposefully fetch them in order to refresh the cache.
be6c8be07a