This moves the block-device default out of the "vm" element and into a
selection of other elements. There's "mbr" which retains the status
quo. There's an EFI version that has the boot/grub partitions as
required. In between there's the GPT only version, which is useful
for architectures like power without EFI, but still want possible
larger disks using GPT.
Change-Id: I4a566a97d073fc0dda0ab2494ac988fe015800a9
The image download tests have long been too unreliable for the gate.
We need to cache the base images similar to how devstack caches it's
testing images. Let's move them to non-voting jobs for the time
being.
This means that the gate jobs are now all based on "-minimal" and are
using infra mirrors. Unfortunately, there is still some unreliability
because we currently have issues with infra mirrors being very slow
after AFS updates, leading to job timeouts. But we're on the right
path...
Also, I noticed we don't have tests of the "ubuntu" image-download
based tests, which were tacitly being tested by apt-sources before we
moved that to -minimal. Add simple tests for these.
Change-Id: Ie33ee49656872467ef68d753210032156bb6b2cb
