[CheckpointExecutor] Remove unneccesary asyncs (#18110)

## Description 

As in title

## Test plan 

It compiles

---

## Release notes

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crates/sui-core/src/checkpoints/checkpoint_executor/mod.rs

@@ -354,7 +354,7 @@ impl CheckpointExecutor {
  .set(is_inconsistent_state as i64);
  }
 
- async fn bump_highest_executed_checkpoint(&self, checkpoint: &VerifiedCheckpoint) {
+ fn bump_highest_executed_checkpoint(&self, checkpoint: &VerifiedCheckpoint) {
  // Ensure that we are not skipping checkpoints at any point
  let seq = *checkpoint.sequence_number();
  debug!("Bumping highest_executed_checkpoint watermark to {seq:?}");
@@ -434,7 +434,7 @@ impl CheckpointExecutor {
  .accumulate_running_root(epoch_store, checkpoint.sequence_number, checkpoint_acc)
  .await
  .expect("Failed to accumulate running root");
- self.bump_highest_executed_checkpoint(checkpoint).await;
+ self.bump_highest_executed_checkpoint(checkpoint);
  }
  }
 
@@ -689,7 +689,7 @@ impl CheckpointExecutor {
  .await
  .expect("Accumulating epoch cannot fail");
 
- self.bump_highest_executed_checkpoint(checkpoint).await;
+ self.bump_highest_executed_checkpoint(checkpoint);
 
  return true;
  }