Removing V2 suffix from fulfillmentCreateV2 and fulfillmentTrackingInfoUpdateV2

As of 2024-10, we're deprecating fulfillmentCreateV2 and fulfillmentTrackingInfoUpdateV2. Instead, please use fulfillmentCreate and fulfillmentTrackingInfoUpdate.

Note that the behavior of the new mutations remains the same as the previous ones; the only change is the removal of V2 to ensure consistent naming across all mutations.