This keeps the `OrderBalance` abstraction but removes the old code now
that the feature is enabled for all users in all instances and there are
no bugs reported. It's become dead code.
This removes the N+1 queries caused by
`Api::Admin::OrderSerialier#ready_to_capture` when used from
`Api::OrdersController#index`. While it's fine for the single-order
controller actions, it's not for this one that deals with a collection
of orders.
Fortunately, `SearchOrders` is used only in this controller action so we
can put the `includes` calls there, otherwise, we would need to refactor
it a bit to pass in a context-specific AR relation.
This makes it possible to deploy it without releasing it to users since
the toggle is not enabled for anyone.
It aims to make the balance calculation consistent across pages.
It's simpler and many orders of magnitude more efficient to ask the DB
to aggregate the customer balance based on their orders. It removes
a nasty N+1.
The resulting SQL query is:
```sql
SELECT customers.*, SUM(spree_orders.total - spree_orders.payment_total) AS balance
FROM "customers"
INNER JOIN "spree_orders"
ON "spree_orders"."customer_id" = "customers"."id"
WHERE "customers"."enterprise_id" = 1
AND (completed_at IS NOT NULL)
AND (state != 'canceled')
GROUP BY customers.id
ORDER BY email;
```
This is only needed in one place, and only as a count, and can cause huge amounts of superfluous data to be fetched and serialized, for example in the admin products index page (where variant override data is not used at all).
This relation is only used above for a call to empty? so we don't need to worry about the select part of the query, specially not introducing an expensive DISTINCT
Prior to this change, there was no way of knowing how much was owed (or
in need of refunding) at a glance for each order on the orders index page,
this information was only available by clicking through to an order
payment page
This change adds the outstanding balance for each order
Here we are copy pasting and adding stripe SCA because we are planning to delete the StripeConnect that will be replaced by the stripe sca implementation
