Downgrade some logs to INFO level. (#4838)

## Motivation

We have several WARN- and ERROR-level logs that can occur during normal
operations, without a faulty validity threshold among the validators.

## Proposal

Downgrade them to INFO.

## Test Plan

(Only log level changes.)

## Release Plan

- These changes should be backported to `testnet_conway`, then
    - be released in a new SDK. (Low priority.)

## Links

- [reviewer
checklist](https://github.com/linera-io/linera-protocol/blob/main/CONTRIBUTING.md#reviewer-checklist)

Author: afck

linera-core/src/client/mod.rs

@@ -373,7 +373,7 @@ impl<Env: Environment> Client<Env> {
                 .download_certificates_from(&remote_node, chain_id, target_next_block_height)
                 .await
             {
-                Err(err) => warn!(
+                Err(err) => info!(
                     "Failed to download certificates from validator {:?}: {err}",
                     remote_node.public_key
                 ),
@@ -1207,7 +1207,7 @@ impl<Env: Environment> Client<Env> {
                             {
                                 Ok(content) => content,
                                 Err(err) => {
-                                    warn!(
+                                    info!(
                                         "Skipping proposal from {owner} and validator {} at \
                                         height {}; failed to download {blob_id}: {err}",
                                         remote_node.public_key, local_info.next_block_height
@@ -3227,7 +3227,7 @@ impl<Env: Environment> ChainClient<Env> {
         if let Some(round_timeout) = info.manager.round_timeout {
             if round_timeout <= self.storage_client().clock().current_time() {
                 if let Err(e) = self.request_leader_timeout().await {
-                    warn!("Failed to obtain a timeout certificate: {}", e);
+                    debug!("Failed to obtain a timeout certificate: {}", e);
                 } else {
                     info = self.chain_info_with_manager_values().await?;
                 }
@@ -3912,7 +3912,7 @@ impl<Env: Environment> ChainClient<Env> {
                     )
                     .await?;
                 if self.local_next_height_to_receive(origin).await? <= height {
-                    warn!(
+                    info!(
                         chain_id = %self.chain_id,
                         "NewIncomingBundle: Fail to synchronize new message after notification"
                     );
@@ -3941,7 +3941,7 @@ impl<Env: Environment> ChainClient<Env> {
                             .await?
                             <= height
                         {
-                            error!("NewBlock: Fail to synchronize new block after notification");
+                            info!("NewBlock: Fail to synchronize new block after notification");
                         }
                         trace!(
                             chain_id = %self.chain_id,
@@ -4034,7 +4034,7 @@ impl<Env: Environment> ChainClient<Env> {
                     return Ok(());
                 };
                 if (info.next_block_height, info.manager.current_round) < (height, round) {
-                    error!(
+                    info!(
                         chain_id = %self.chain_id,
                         "NewRound: Fail to synchronize new block after notification"
                     );
@@ -4173,7 +4173,7 @@ impl<Env: Environment> ChainClient<Env> {
             })
             .filter_map(move |result| async move {
                 if let Err(error) = &result {
-                    warn!(?error, "Could not connect to validator {public_key}");
+                    info!(?error, "Could not connect to validator {public_key}");
                 } else {
                     debug!("Connected to validator {public_key}");
                 }
@@ -4197,7 +4197,7 @@ impl<Env: Environment> ChainClient<Env> {
                         )
                         .await
                     {
-                        tracing::warn!(
+                        tracing::info!(
                             chain_id = %this.chain_id,
                             validator_public_key = ?remote_node.public_key,
                             ?notification,

linera-core/src/remote_node.rs

@@ -22,7 +22,7 @@ use linera_chain::{
     },
 };
 use rand::seq::SliceRandom as _;
-use tracing::{debug, instrument, warn};
+use tracing::{debug, info, instrument};
 
 use crate::{
     data_types::{ChainInfo, ChainInfoQuery, ChainInfoResponse},
@@ -186,7 +186,7 @@ impl<N: ValidatorNode> RemoteNode<N> {
     ) -> Result<ConfirmedBlockCertificate, NodeError> {
         let certificate = self.node.blob_last_used_by_certificate(blob_id).await?;
         if !certificate.block().requires_or_creates_blob(&blob_id) {
-            warn!(
+            info!(
                 "Got invalid last used by certificate for blob {} from validator {}",
                 blob_id, self.public_key
             );
@@ -338,13 +338,13 @@ impl<N: ValidatorNode> RemoteNode<N> {
         let public_key = &self.public_key;
         for blob_id in blob_ids {
             if !required.contains(blob_id) {
-                warn!("validator {public_key} requested blob {blob_id:?} but it is not required");
+                info!("validator {public_key} requested blob {blob_id:?} but it is not required");
                 return Err(NodeError::UnexpectedEntriesInBlobsNotFound);
             }
         }
         let unique_missing_blob_ids = blob_ids.iter().copied().collect::<HashSet<_>>();
         if blob_ids.len() > unique_missing_blob_ids.len() {
-            warn!("blobs requested by validator {public_key} contain duplicates");
+            info!("blobs requested by validator {public_key} contain duplicates");
             return Err(NodeError::DuplicatesInBlobsNotFound);
         }
         Ok(())