removed test images to reduce project size

[LTDakin]

these were used during the skeleton phase of datalab when we didn't have archive data. cleaning them up

[mgdaily]

Nice. These will still be present in the git history, however, so we should probably remove them all from the git history as well. Otherwise they will still be present (though, hidden) every time someone clones the repository.

GitHub has a guide about this:

https://docs.github.com/en/authentication/keeping-your-account-and-data-secure/removing-sensitive-data-from-a-repository

[LTDakin]

Putting this on pause until all other PRs are merged (required by BFG repo cleaner to properly clean the files)