Remove 'placement_group' from advanced settings
Remove 'placement_group' from advanced settings

Now that there is a dedicated PlacementGroup model there's no need to
also have an entry in advanced settings. Further, this prevents active
record calls from finding a Vm's associated PlacementGroup.

jrafanie/manageiq,kbrock/manageiq,kbrock/manageiq,ManageIQ/manageiq,jrafanie/manageiq,ManageIQ/manageiq,kbrock/manageiq,jrafanie/manageiq,ManageIQ/manageiq,ManageIQ/manageiq,kbrock/manageiq,jrafanie/manageiq