fix(build_library/legacy_disk_layout): Use coreos- prefixes
fix(build_library/legacy_disk_layout): Use coreos- prefixes

vboot_reference now recognizes coreos-reserved and coreos-rootfs. Use
these prefixes so we stop using the chromeos GUIDs.

Test-plan: Tested on a VM and it boots and updates.

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