Move the last remaining test into the correct subdir. With this done,
all our tests run in one of the 3 groups:
* `make test-src`
Run tests against the source-code, including linters.
* `make test-mod`
Run unit-tests on the individual python modules. This needs no
special permissions (unless noted in each test) or runtime
environments. It is meant to be fast and easy to run in all
circumstances.
* `make test-run`
Run tests that execute the osbuild pipeline. This requires
superuser privileges and will likely take a while. Furthermore,
this might produce large artifacts.
