Optimize pending acks cleanup by mark delete position in PersistentDispatcherMultipleConsumers

> Another difference is https://github.com/apache/pulsar/blob/f2618c15bb5a9f3fcb577068584df5d0e2e4f335/pulsar-broker/src/main/java/org/apache/pulsar/broker/service/persistent/PersistentDispatcherMultipleConsumers.java#L361-L370 which is important for PIP-379. It might need to be optimized so that it's run asynchronously and batched in a way that multiple mark delete updates would only run for the latest update at most once per second.

_Originally posted by @lhotari in [#24490](https://github.com/apache/pulsar/issues/24490#issuecomment-3056496751)_