MaxOneThreadPerSender was created to reduce the number of threads and thus context switching. With virtual threads, this is not needed anymore and we might simply bypass the queue/sender in this class, and send the message or batch up the stack in a virtual thread.

This mostly applies to regular messages/batches, as OOB msgs/batches are passed directly to the thread pool in the current code. Measure the impact of this on regular msgs/batches.

Todo: use the existing behavior when using regular threads and switch to the new behavior when using virtual threads.