Try running tests on self-hosted runners (#1812)

* Try running tests on self-hosted runners

* Update pipeline.yml

* Update pipeline.yml

* Update pipeline.yml

* Update pipeline.yml

* Update check.nix

* Does this fix check-hydra?

* We need a ghc to unpack... I guess.

Co-authored-by: Moritz Angermann <moritz.angermann@gmail.com>

Author: hamishmack