Set log level to debug for preview deployment

Also, add a log statement when we receive the interrupt signal.

Co-Authored-By: Max Brunsfeld <max@zed.dev>

crates/collab/k8s/environments/preview.sh

@@ -1,3 +1,3 @@
 ZED_ENVIRONMENT=preview
-RUST_LOG=info
+RUST_LOG=debug
 INVITE_LINK_PREFIX=https://zed.dev/invites/

crates/collab/src/main.rs

@@ -69,6 +69,7 @@ async fn main() -> Result<()> {
                     tokio::signal::ctrl_c()
                         .await
                         .expect("failed to listen for interrupt signal");
+                    tracing::info!("Received interrupt signal");
                     rpc_server.teardown();
                 })
                 .await?;