mfi-common: Rework toolstack-disk_format test matrix

mfi-common: Rework toolstack-disk_format test matrix

There is 6 potenteil test of toolstack disk_format combination:
{xl,libvirt}-{raw,vhd,qcow2}. Commit f536e834f673 ("make-flight: Trim
the matrix of disk format flights") introduced a way to avoid testing
on every architecture and actually do only 6 tests accross all
arches, 3 on x86, 3 on armhf (no arm64 at the time).

But, commit 5c70735f177f ("fmtarches: Use dom0arches, not hardcoded
arch list") broke that. There's an extra space ' ' added at the
begining of the string in variable $fmtarches_outer which break the
algorithm. This mean that the combination of xl+raw is never tested
and both armhf and amd64 are testing the same combination of
toolstack+disk_format.

We could just remove the extra ' ', but that would mean 3 extra tests
on armhf and 3 extra tests on arm64. At least x86 would have a test
for each combination.

I'd like to avoid adding more arm* tests due to limited capacity, so
the new goal is to have the 6 combination of toolstack-disk_format
spread on both arm*, where each get to test all possible disk_format.
On x86, we are also going to tests all 6 combinations, which might all
happen on dom0=amd64 if we don't test dom0=i386, or they will be
spread on both kind of dom0.

To avoid too many changes in jobs on x86 with the current list of
jobs, we reverse the order of "i386" and "amd64".

Jobs changes on xen-unstable and most branches:
x86:
+ test-amd64-amd64-xl-raw
+ test-amd64-i386-libvirt-qcow2
arm*:
- test-armhf-armhf-libvirt-qcow2
- test-armhf-armhf-libvirt-raw
- test-armhf-armhf-xl-vhd
+ test-armhf-armhf-libvirt-vhd
+ test-armhf-armhf-xl-qcow2
+ test-armhf-armhf-xl-raw

Jobs changes on linux-{linus,next,6.1}:
x86:
+ test-amd64-amd64-libvirt-vhd
+ test-amd64-amd64-xl-qcow2
+ test-amd64-amd64-xl-raw
arm*:
- test-armhf-armhf-libvirt-qcow2
- test-armhf-armhf-libvirt-raw
- test-armhf-armhf-xl-vhd
+ test-armhf-armhf-libvirt-vhd
+ test-armhf-armhf-xl-qcow2
+ test-armhf-armhf-xl-raw

Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>