This fixes the error UK's is experiencing:
```
PG::AmbiguousColumn: ERROR: column reference "state" is ambiguous LINE
1: SELECT DISTINCT spree_orders.*, CASE WHEN state IN ('cancele...
^ : SELECT DISTINCT spree_orders.*, CASE WHEN state IN ('canceled',
'returned') THEN payment_total WHEN state IS NOT NULL THEN payment_total
- total ELSE 0 END AS balance_value, spree_orders.* FROM "spree_orders"
INNER JOIN "spree_shipments"
```
See
https://app.bugsnag.com/yaycode/openfoodnetwork-uk/errors/6058c45989d37300079e8312?event_id=6058ccd30075af73bcb20000&i=sk&m=nw.
In this class we properly calculated the balance taking into account the
orders in cancellation state so we need to use the new implementation if
we don't want to introduce a regression by using
`#old_oustanding_balance`.
I was initially a bit dubious because this method was checking
`order.payments` as well but now I see that was redundant. Is on
`payment_total` to take into account whether or not the order is paid or
any other payment related details.
This class is currently used and it gets skipped when the
:customer_balance toggle is enabled, so there's no point on abstracting
the balance with `OrderBalance`. It'll never go through its
`#new_outstanding_balance` branch and it'll be removed once we active
that toggle to everyone.
This will let us branch by abstraction. All existing calls to
`#outstanding_balance` will go through `OrderBalance` hence, will
check the feature toggle.
Note that by default, `OrderBalance` will end up calling
`#old_outstanding_balance`. As the name states, that's exactly what
`#outstanding_balance` was so far. This means no consumers will see any
change in behavior. We just added on item in the call stack (sort of).
We observed invalid payment states in Bugsnag but we don't actually know
in which state the payment intent was in. From the context we can guess
that it was "succeeded" but it would be good to validate this. And in
the future it would be good to know if there are other invalid states we
can end up in.
The notification to Bugsnag happens in another part of the code.
