Add deployment type in the metadata

The QA report app now relies on heuristics to determine the deployment type, and it some cases it gets it wrong: for instance it looks for the ostree string in the URL, so it had misclassified SDK images like https://images.apertis.org/test/wip-em-ostree-only-pull-metadata/daily/v2021dev2/20200412.1719/amd64/sdk/apertis_v2021dev2-sdk-amd64-sdk_20200412.1719.img.gz

If we set the right metadata the heuristics will be ignored.