message: trival: remove unused functions on TreeState
  is_empty() not used
  new_for_testing() used only in fuzzing, not testing.
diff: @@ -59,7 +59,7 @@ impl StartupInfo {
  }
  }
  - #[cfg(any(test, feature = "fuzzing"))]
  + #[cfg(any(feature = "fuzzing"))]
  pub fn new_for_testing() -> Self {
  use libra_types::on_chain_config::ValidatorSet;
  @@ -113,11 +113,6 @@ impl TreeState {
  }
  }
  - pub fn is_empty(&self) -> bool {
  - self.num_transactions == 0
  - && self.account_state_root_hash == *SPARSE_MERKLE_PLACEHOLDER_HASH
  - }
  -
  pub fn describe(&self) -> String {
  if self.num_transactions != 0 {
  format!(
  