remove spurious error lines (aptos-labs#12137)

Author: igor-aptos

consensus/src/quorum_store/batch_store.rs

@@ -349,7 +349,7 @@ impl BatchStore {
         match self.db.get_batch(digest) {
             Ok(Some(value)) => Ok(value),
             Ok(None) | Err(_) => {
-                error!("Could not get batch from db");
+                warn!("Could not get batch from db");
                 Err(ExecutorError::CouldNotGetData)
             },
         }

consensus/src/round_manager.rs

@@ -777,7 +777,7 @@ impl RoundManager {
             while start.elapsed() < Duration::from_millis(timeout_ms) {
                 if !block_store.vote_back_pressure() {
                     if let Err(e) = self_sender.push(author, event) {
-                        error!("Failed to send event to round manager {:?}", e);
+                        warn!("Failed to send event to round manager {:?}", e);
                     }
                     break;
                 }