This patch adds code that tries to read the partition table after we've
successfully written an image to make sure the image that we wrote has a
valid partition table so we can more easily guarantee that what we've
written is bootable and not just junk. Without a valid partition table
writing a config drive will fail for whole disk images.
Co-Authored-By: Dmitry Tantsur <dtantsur@redhat.com>
Change-Id: I5cfd8c433a4db3e0d2d5086250e629d16234b7a4
Story: 2001760
Task: 12159