Store the ref. images and summary.html

Pick the ref images and the summary html files in the artefacts.

If we want to avoid double-storing the ref. images we could: a) have the ref. thumbnail in the traces-db repo. Note: in some cases apitrace may not produce thumbnails b) tweak the ref. URLs (in summary.html) pointing to the respective files in the traces-db repo

Another completely different route is: a) create a "dummy" account for the traces-db repo b) use the credentials (safely) so that tracie gitlab-ci, uploads the test images to traces-db c) for trivial deduplication of files in traces-db, we can use store a image named after its sha. With individual instances being a link to it.

But all that for another day.