[OrderBundle] Skip adjustments on empty carts

Fixed #1310. Skips adjustments when calculating total price on empty carts.

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #1310
| License       | MIT
| Doc PR        | -