Fix "invisible" CI tests #1

Job	Run time
build-cache / Build and cache OpenMPI 5	39s
domain-decomp / Run domain decomposition unit tests	1m 7s
pip-install / test-pip-install	1m 12s
adaptivity-serial / Unit and integration tests	1m 11s
integration-dummy / Run dummy	1m 19s
coverage / Run test coverage check	1m 22s
adaptivity-parallel / Unit tests	1m 3s
adaptivity-parallel / Integration tests	1m 17s
unit-tests / unit_tests	1m 12s
	10m 22s

Provide feedback