message: Reorganize handler for `Event::Prune` and add comments
diff: @@ -264,14 +264,15 @@ impl BlockProposerReady {
  Effects::new()
  }
  Event::Prune => {
  - let pruned_hashes = self.prune(Timestamp::now());
  - let pruned_count = pruned_hashes.total_pruned;
  - debug!(%pruned_count, "pruned deploys from buffer");
  -
  + // Re-trigger timer after `PRUNE_INTERVAL`.
  let mut effects = effect_builder
  .set_timeout(PRUNE_INTERVAL)
  .event(|_| Event::Prune);
  + // Announce pruned hashes
  + let pruned_hashes = self.prune(Timestamp::now());
  + let pruned_count = pruned_hashes.total_pruned;
  + debug!(%pruned_count, "pruned deploys from buffer");
  effects.extend(
  effect_builder
  .announce_expired_deploys(pruned_hashes.expired_hashes_to_be_announced)
  