auto-attach subscription may trigger some corner case

[Rocco83]

In a VDC environment, has been observed that in case of a guest already has some subscription other then RHEL/Smart Management, running auto-attach may remove the specific subscription.
Even if this is a bug on auto-attach, a workaround or a better way to manage the auto-attach should be in the code.
one possibility can be to catch all the VDC subscriptions present on the specific host (part of a cluster) and attach it directly.