By default, ESXi creates a swap file with the size of the VM's configured memory. Since this seems to be a stand-alone host, and there's no memory overcommitment (as far as I understand it), you may change the VM's settings and set/increase the "Memory Reservation". The swap file size will then be "assigned memory" minus "reservation", i.e. if you set the reservation to 128GB, the swap file size on the datastore will be zero.
André