Fix docker driver MemorySwap value
Fix docker driver MemorySwap value

Fixes an incorrect value being assigned to MemorySwap when `memory_hard_limit` flag is being used.

Issue raised in https://github.com/hashicorp/nomad/issues/8153
burdandrei/nomad,hashicorp/nomad,burdandrei/nomad,hashicorp/nomad,hashicorp/nomad,dvusboy/nomad,dvusboy/nomad,hashicorp/nomad,burdandrei/nomad,burdandrei/nomad,burdandrei/nomad,dvusboy/nomad,dvusboy/nomad,dvusboy/nomad,burdandrei/nomad,burdandrei/nomad,dvusboy/nomad,hashicorp/nomad,dvusboy/nomad,hashicorp/nomad