fix(medusa): Incorrect swap difference due (#2086)

### What
Creating a swap on an order with a discount leads to an incorrect difference due. 

**Scenario**
- Create a store with minimum 2 products (Prod A, Prod B)
- Create a discount that only works for Prod A
- Create an order for Prod A with the discount applied
- Create a swap between Prod A and Prod B

**Expected outcome**
We would expect the difference_due amount to come out to the sum of:
- -1 * (price of prod a - discount applied to prod a) 
- price of prod b

**Actual outcome**
Instead the discount is applied across both products when calculating difference due. This results in a total that is instead the sum of:
- -1 * (price of prod a - discount applied to prod a)
- price of prod b - discount on prod b ignoring the condition

### How
Adds `line_item.adjustments` to relations in cart retrieval prior to setting the difference_due to car total

Fixes CORE-361

integration-tests/api/__tests__/totals/orders.js

@@ -30,6 +30,7 @@ describe("Order Totals", () => {
       medusaProcess = await setupServer({ cwd })
     } catch (error) {
       console.log(error)
+      throw error
     }
   })