downgrade bootstrap log channel tracing (meta-pytorch#810)

Summary:
Pull Request resolved: meta-pytorch#810

not an important log line; lower it to debug

Reviewed By: zdevito

Differential Revision: D79926027

fbshipit-source-id: b8c4db3fee6f2769430a82c32206f12a1b92cca7

Author: highker

hyperactor_mesh/src/logging.rs

@@ -560,7 +560,7 @@ impl Actor for LogForwardActor {
         let log_channel: ChannelAddr = match std::env::var(BOOTSTRAP_LOG_CHANNEL) {
             Ok(channel) => channel.parse()?,
             Err(err) => {
-                tracing::error!(
+                tracing::debug!(
                     "log forwarder actor failed to read env var {}: {}",
                     BOOTSTRAP_LOG_CHANNEL,
                     err