fix(legacy_disk_layout.json): Omit unused partitions.
fix(legacy_disk_layout.json): Omit unused partitions.

We don't need to reserve space on disk just to reserve partition
numbers. And now that partitions are aligned these blanks spots grew
from 512 bytes to 1MB which is not much but still silly.

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