Follow-up from "Add new GraphQL query getAddOnPurchases"

The following discussion from !160515 (merged) should be addressed:

• @bhrai started a discussion: (+2 comments)

  suggestion (non-blocking): To avoid N + 1 , we can add includes for add_on and add_on_assignments , which gets called in AddOnPurchaseType . Since, it's a graphql we could look into adding preloads ?

  Also, the authroization will get called for each record too, IIUC. May be we could see a way to preload it too? This may only be needed for gitlab_com_subscription and namespace . Existing example.