Enable test repo earlier in image generation

Test on MR requires to install updated version of packages, which might have been installed in ospack, or are being installed as part of the hardware pack. One special package is the linux kernel, which requires lots of space and by default keeps the previous version to ensure a fallback option.

In order to avoid the size restrictions of images enable the repo earlier in the image generation, in order to install only the latest version of the linux package.

Also provide a few improvements to make the test on MR cleaner.

Signed-off-by: Walter Lozano walter.lozano@collabora.com