openqa: Move tests into separate repo
Currently, opening an MR for an OpenQA test has a 2-hour iteration time, because the full gnome-build-meta pipeline has to run each time you update your branch, and the tests only run once that's complete. This includes 70 minutes to build the .iso each time.
The needles are in a separate openqa-needles repo and updating a needle is a 2 minute job, you can rerun the tests for any gnome-build-meta pipeline without a rebuild and the updated tests will be pulled for master branch.
Branching is a consideration: openqa-needles has only a 'master' branch, which contains needles for every version of GNOME we might test. (This is the approach recommended by OpenQA upstream). For openqa-tests, I propose we use branch names corresponding to gnome-build-meta, i.e. gnome-41 tests on gnome-41 branch, master tests on master branch. The CI can clone the tests at $CI_BRANCH_NAME, falling back to master.