Future Ohai: Remove legacy data in the Virtualization plugin

[tas50]

Before we introduced node['virtualization']['systems'] we used node['virtualization']['system'] and node['virtualization']['role']. This only allowed for a single virtualization, but we detected multiple technologies so the last writer won. We introduced the systems array in Chef 11 (pretty sure) which provides a much more reliable way to detect virtualization systems. We should create a Foodcritic rule and move people to the new system so we can fully deprecate the less than ideal older interface.

Scenario where the old interfaces fail:

virtualization
    systems
        kvm: host
        vmware: host
    system: vmware
    role: guest

[btm]

@tas50 is there a cookstyle rule for this?

[tas50]

There is not. We probably need to have a rule in place for a while before we can consider removing anything.