This fixture will collect references to pulp objects to be deleted after
a test. It will attempt deletion in reversed order and await all tasks
in parallel.
Rationale: In pulp container we create Distributions and namespaces by push operations, so we cannot use gen_object_with_cleanup there. Also we do not have unittest.TestCase.teardown() available anymore.
This fixture will collect references to pulp objects to be deleted after a test. It will attempt deletion in reversed order and await all tasks in parallel.