Don't auto-create Tenants group

Django makes it impossibly difficult to manipulate groups and
permissions during initialization (eg. from migrations).
See eg. https://stackoverflow.com/q/67232243/1839209.

tenants/apps.py

@@ -4,27 +4,3 @@ from django.apps import AppConfig
 class TenantsConfig(AppConfig):
     default_auto_field = 'django.db.models.BigAutoField'
     name = 'tenants'
-
-    def ready(self):
-        super().ready()
-        _ensure_tenants_group_exists()
-
-
-def _ensure_tenants_group_exists():
-    """
-    Make sure the "Tenants" group exists so users can be assigned to it.
-    Normally, we would want to do this in a migration. Unfortunately, Django
-    cannot currently (easily) assign permissions in a migration [1].
-    The `ready()` method above seems like a reasonable place to do it instead.
-    """
-    # We cannot import the following at the module level because Django has not
-    # been initialized yet:
-    from django.contrib.auth.models import Group, Permission
-    from winget.models import Package, Version, Installer
-    group, created = Group.objects.get_or_create(name='Tenants')
-    if created:
-        for model in (Package, Version, Installer):
-            for action in ('view', 'add', 'change', 'delete'):
-                codename = f'{action}_{model._meta.model_name}'
-                permission = Permission.objects.get(codename=codename)
-                group.permissions.add(permission)