message: [backup] backup coordinator: always use 1 as epoch ending backup batch size
  Tt's always desirable to backup epoch ending LedgerInfo as soon as possible, otherwise other backup types can fail to verify.
  Closes:
diff: @@ -28,10 +28,6 @@ use tokio::{
  pub struct BackupCoordinatorOpt {
  #[structopt(flatten)]
  pub metadata_cache_opt: MetadataCacheOpt,
  - // Assuming epoch doesn't bump frequently, we default to backing epoch ending info up as soon
  - // as possible.
  - #[structopt(long, default_value = "1")]
  - pub epoch_ending_batch_size: usize,
  // We replay transactions on top of a state snapshot at about 2000 tps, having a state snapshot
  // every 2000 * 3600 * 2 = 14.4 Mil versions will guarantee that to achieve any state in
  // history, it won't take us more than two hours in transaction replaying. Defaulting to 10 Mil
  @@ -48,10 +44,8 @@ pub struct BackupCoordinatorOpt {
  impl BackupCoordinatorOpt {
  fn validate(&self) -> Result<()> {
  ensure!(
  - self.epoch_ending_batch_size > 0
  - && self.state_snapshot_interval > 0
  - && self.transaction_batch_size > 0,
  - "Backup interval and batch sizes must be greater than 0"
  + self.state_snapshot_interval > 0 && self.transaction_batch_size > 0,
  + "Backup interval and batch size must be greater than 0."
  );
  Ok(())
  }
  @@ -62,7 +56,6 @@ pub struct BackupCoordinator {
  storage: Arc<dyn BackupStorage>,
  global_opt: GlobalBackupOpt,
  metadata_cache_opt: MetadataCacheOpt,
  - epoch_ending_batch_size: usize,
  state_snapshot_interval: usize,
  transaction_batch_size: usize,
  }
  @@ -80,7 +73,6 @@ impl BackupCoordinator {
  storage,
  global_opt,
  metadata_cache_opt: opt.metadata_cache_opt,
  - epoch_ending_batch_size: opt.epoch_ending_batch_size,
  state_snapshot_interval: opt.state_snapshot_interval,
  transaction_batch_size: opt.transaction_batch_size,
  }
  @@ -171,10 +163,7 @@ impl BackupCoordinator {
  db_state: DbState,
  downstream_db_state_broadcaster: &watch::Sender<DbState>,
  ) -> Result<Option<u64>> {
  - let (first, last) = get_batch_range(
  - last_epoch_ending_epoch_in_backup,
  - self.epoch_ending_batch_size,
  - );
  + let (first, last) = get_batch_range(last_epoch_ending_epoch_in_backup, 1);
  let next_state = if db_state.epoch <= last {
  // "<=" because `db_state.epoch` hasn't ended yet, wait for the next db_state update
  