ami: switch back to raw disk images by default
ami: switch back to raw disk images by default

Unsure if the VMDK images are a factor in recent corruption issues
recently or not. Until that is sorted out go back to our old ways.

nicescale/scripts,glevand/coreos--scripts,trnubo/scripts,trnubo/scripts,smilart/scripts,marineam/coreos-scripts,nicescale/scripts,sigma/coreos-scripts,mjg59/scripts,nicescale/scripts,sigma/coreos-scripts,marineam/coreos-scripts,marineam/coreos-scripts,coreos/scripts,coreos/scripts,sigma/coreos-scripts,trnubo/scripts,mjg59/scripts,smilart/scripts,mjg59/scripts,glevand/coreos--scripts,smilart/scripts