chore(medusa): rm default created at field (#8213)

**What**
To maintain the backward compatibility, we use to populate `created_at` no matter what. But since we can break things from v1, I ll remove it as we moved the default ordering to the repository layer

integration-tests/api/__tests__/store/products.js

@@ -13,7 +13,7 @@ const adminSeeder = require("../../../helpers/admin-seeder")
 const {
   allowedStoreProductsFields,
   defaultStoreProductsRelations,
-} = require("@medusajs/medusa/dist")
+} = require("@medusajs/medusa")
 
 const adminHeaders = {
   headers: {