CI default tests for async branch are completely broken

[jinnatar]

Any PR to branch async triggers a tox run. The env for the run comes from docker/.dev.env but even if I patch it for async compat with:

THERAIDMAPPER_APK_STORAGE_INTERFACE=fs
THERAIDMAPPER_CACHE_HOST=redis

.. that just triggers more failures that seem to indicate most tests were never ported for async.

I propose deleting the tests since they:

1. Make most PRs to async fail automated checks (that can never succeed)
2. Provide a false sense of security, since clearly they aren't actually testing for anything since they are nonfunctional.

As they've been in this state for quite a while, I'm assuming fixing the tests is not a priority. Hence I'm proposing deleting most of them as dead weight, allowing any actually functioning tests to run cleanly. (Assuming any of them actually work, I'm not seeing any succeed.)