Sort test results by image_build

After commit 80c00c5c the main page shows results grouped by release, changing the previous sort order by build. Sort by build is preferable to easily see the status of last builds for all the supported releases and also aligns with how results are sorted in the full page.

Fix the issue by sorting the results by build.

https://phabricator.apertis.org/T9487

https://phabricator.apertis.org/T9232

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