When the deployment happens on a GPT disk with config drive, writing
it to disk fails. Three reasons for that:
* parted should be used instead of partprobe to determine the type of
the disk;
* gdisk -l sorts the partitions by their number, sort them by start
sector instead;
* after sgdisk completion, the configdrive device is not immediately
visible in the /dev folder, udevadm settle needed here too.
Closes-Bug: #1633063
Change-Id: Ifed89e343f9db4cf303baf7f8823342f6041f202
7bda3408f5