[sui-node/logging] (#19301)

## Description
move warn to error when sui-node cannot send metrics

## Test Plan
it builds

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## Release notes

Check each box that your changes affect. If none of the boxes relate to
your changes, release notes aren't required.

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that describes the impact of your changes that a user might notice and
any actions they must take to implement updates.

- [ ] Protocol: 
- [ ] Nodes (Validators and Full nodes): 
- [ ] Indexer: 
- [ ] JSON-RPC: 
- [ ] GraphQL: 
- [ ] CLI: 
- [ ] Rust SDK:
- [ ] REST API:

crates/sui-node/src/metrics.rs

@@ -137,7 +137,7 @@ pub fn start_metrics_push_task(config: &sui_config::NodeConfig, registry: Regist
             interval.tick().await;
 
             if let Err(error) = push_metrics(&client, &url, &registry).await {
-                tracing::warn!("unable to push metrics: {error}; new client will be created");
+                tracing::error!("unable to push metrics: {error}; new client will be created");
                 // aggressively recreate our client connection if we hit an error
                 // since our tick interval is only every min, this should not be racey
                 client = MetricsPushClient::new(config_copy.network_key_pair().copy());