Fix detection of user follower collection being private

We were overzealous with matching on a raw error from the object fetch that should have never been relied on like this. If we can't fetch successfully we should assume that the collection is private.

Building a more expressive and universal error struct to match on may be something to consider.

lib/pleroma/web/activity_pub/activity_pub.ex

@@ -1697,9 +1697,7 @@ defp collection_private(%{"first" => first}) do
            Fetcher.fetch_and_contain_remote_object_from_id(first) do
       {:ok, false}
     else
-      {:error, {:ok, %{status: code}}} when code in [401, 403] -> {:ok, true}
-      {:error, _} = e -> e
-      e -> {:error, e}
+      {:error, _} -> {:ok, true}
     end
   end