Fix Cells ImagePropertiesFilter can raise exceptions

In a misconfigured scenario the ImagePropertiesFilter can raise an
exception which causes the image to be unbuildable in the region. This
happens when the capabilities is set for prominent_hypervisor_version
to an empty list.

Change-Id: I17bd9d87fa69ad34b19591018543a34dfd050978
Closes-Bug: 1343462
Merge "Fix Cells ImagePropertiesFilter can raise exceptions"