Remove download threadpool bypass conditional on 14.04 PV
Remove download threadpool bypass conditional on 14.04 PV

This reverts most of 580684d "PTFM-13158 Disable download threadpool
on 14.04 PV". There is no evidence that disabling the download
threadpool helped with the data integrity issue on 14.04 PV.

andyshinn/dx-toolkit,olegnev/dx-toolkit,jhuttner/dx-toolkit,olegnev/dx-toolkit,andyshinn/dx-toolkit,dnanexus/dx-toolkit,dnanexus/dx-toolkit,jhuttner/dx-toolkit,dnanexus/dx-toolkit,johnwallace123/dx-toolkit,jhuttner/dx-toolkit,jhuttner/dx-toolkit,dnanexus/dx-toolkit,andyshinn/dx-toolkit,jhuttner/dx-toolkit,jhuttner/dx-toolkit,andyshinn/dx-toolkit,olegnev/dx-toolkit,andyshinn/dx-toolkit,olegnev/dx-toolkit,olegnev/dx-toolkit,johnwallace123/dx-toolkit,dnanexus/dx-toolkit,johnwallace123/dx-toolkit,jhuttner/dx-toolkit,andyshinn/dx-toolkit,johnwallace123/dx-toolkit,johnwallace123/dx-toolkit,andyshinn/dx-toolkit,olegnev/dx-toolkit,jhuttner/dx-toolkit,johnwallace123/dx-toolkit,andyshinn/dx-toolkit,olegnev/dx-toolkit,dnanexus/dx-toolkit,dnanexus/dx-toolkit,olegnev/dx-toolkit,dnanexus/dx-toolkit,johnwallace123/dx-toolkit,johnwallace123/dx-toolkit