fix(vm_image_util): Remove fstab from PXE initrd
fix(vm_image_util): Remove fstab from PXE initrd

Using fstab made overriding it with kernel command line options like
root=/some/disk not work properly. A generator handles it now.

endocode/scripts,sigma/coreos-scripts,mjg59/scripts,smilart/scripts,andrejro/coreos--scripts,fivethreeo/scripts,coreos/scripts,vmware/coreos-scripts,marineam/coreos-scripts,endocode/scripts,nicescale/scripts,trnubo/scripts,fivethreeo/scripts,trnubo/scripts,marineam/coreos-scripts,zhang0137/scripts,andrejro/coreos--scripts,zhang0137/scripts,glevand/coreos--scripts,andrejro/coreos--scripts,mjg59/scripts,zhang0137/scripts,BugRoger/scripts,endocode/scripts,sigma/coreos-scripts,trnubo/scripts,BugRoger/scripts,smilart/scripts,glevand/coreos--scripts,crawford/scripts,nicescale/scripts,BugRoger/scripts,vmware/coreos-scripts,mischief/scripts,mischief/scripts,nicescale/scripts,gtank/scripts,marineam/coreos-scripts,vmware/coreos-scripts,mischief/scripts,gtank/scripts,smilart/scripts,fivethreeo/scripts,gtank/scripts,sigma/coreos-scripts,coreos/scripts,crawford/scripts,crawford/scripts,mjg59/scripts