remove bank.is_leader, dead code (#1516)

src/fullnode.rs

@@ -553,7 +553,7 @@ impl Fullnode {
         ledger_path: &str,
         leader_scheduler: &mut LeaderScheduler,
     ) -> (Bank, u64, Vec<Entry>) {
-        let bank = Bank::new_default(false);
+        let bank = Bank::default();
         let entries = read_ledger(ledger_path, true).expect("opening ledger");
         let entries = entries
             .map(|e| e.unwrap_or_else(|err| panic!("failed to parse entry. error: {}", err)));