A commit was made in #6315 (5979f25) in service of the in memory order updater #5872 that changed the behavior in the OrderTaxation class to set the adjustment value but not persist it. Instead, the persistence happens when the order is saved. If a shipment is changed, and an associated adjustment is changed, the shipment adjustment will be autosaved when the order is.

However, if a shipment is *not* changed, but the adjustment is, the adjustment will *not* be autosaved when the order is.

In #6315, we ensured that these changed associations cannot get left behind by setting `autosave: true`, which forces the model to check if it has any associations that need saving instead of telling it's relation "nope I haven't changed"

We can do the same thing here for the shipment to ensure changing  adjustments will make the shipment tell it's order "I have changed", even if none of it's direct properties have changed.

You can test this change by removing the `autosave: true` option the adjustments and running 'when the address has changed to a different state' specs. They fail with the error "expected `order.shipments.first.adjustments.first.amount` to have changed from 1 to 2, but did not change", demonstrating a scenario where the shipment adjustment changes do not get persisted.

(cherry picked from commit b47e0f0)