ref: handle AnonymousUser in organization_index (#91562)

new django-stubs properly types `AnonymousUser.id` -- this fixes the
usage in this view

<!-- Describe your PR here. -->

Author: asottile-sentry

src/sentry/api/endpoints/organization_index.py

@@ -105,7 +105,7 @@ def get(self, request: Request) -> Response:
             elif request.auth.organization_id is not None:
                 queryset = queryset.filter(id=request.auth.organization_id)
 
-        elif owner_only:
+        elif owner_only and request.user.is_authenticated:
             # This is used when closing an account
 
             # also fetches organizations in which you are a member of an owner team