batch_size_fail_threshold_in_kb does not account for LWTs

Subject probably says it all, but basically there's a batch_size_warn_threshold_in_kb and batch_size_fail_threshold_in_kb in the config but these don't apply to LWTs.

So of course I found a situation in which devs were doing LWT operations of many megabytes

Can we make it possible to forbid these, the same way it can be done for batches?