fix(medusa): Optimize Cart totals calculation (#2372)

**What**

The existing totals calculations are extremely heavy and perform an enormous amount of duplicate work. The changes here remove large parts of the overhead and improves response times for cart endpoints up to 30x.

integration-tests/api/__tests__/admin/order/order.js

@@ -32,7 +32,7 @@ describe("/admin/orders", () => {
   beforeAll(async () => {
     const cwd = path.resolve(path.join(__dirname, "..", "..", ".."))
     dbConnection = await initDb({ cwd })
-    medusaProcess = await setupServer({ cwd })
+    medusaProcess = await setupServer({ cwd, verbose: false })
   })
 
   afterAll(async () => {