Cleanup

The `unit/apikey` directory is removed because it does not contain any
tests. Same for `unit/test_decorators.py`.
The `fixture` module is renamed to the special-name `conftest` [0] so
they are available in all tests without the need to import them. With
that in place, I removed all now unneeded or previously already unused
imports from the tests.
Also removed that wierd `sys.path` bit from `unit/zone/test_admin_apikey.py`,
no idea what that was originally intended for.

[0] https://docs.pytest.org/en/6.2.x/fixture.html#conftest-py-sharing-fixtures-across-multiple-files

tests/integration/api/management/test_admin_user.py

@@ -1,9 +1,5 @@
-
 import json
-from tests.fixtures import (    # noqa: F401
-    client, initial_data, basic_auth_admin_headers,
-    test_admin_user, test_user, account_data, user1_data,
-)
+
 from . import IntegrationApiManagement
 
 

tests/integration/api/management/test_user.py

@@ -1,10 +1,6 @@
 
 import json
 
-from tests.fixtures import (    # noqa: F401
-    client, initial_data, basic_auth_admin_headers, basic_auth_user_headers,
-    test_admin_user, test_user, account_data, user1_data,
-)
 from . import IntegrationApiManagement