chore: remove unused instance_id import in main.rs

apps/app/src/main.rs

@@ -7,7 +7,7 @@ use db::cache::AppCache;
 use db::database::AppDatabase;
 use observability::{
     init_tracing_subscriber, install_recorder, prometheus_handler, spawn_http_metrics_poller,
-    HttpMetrics, HttpSnapshotGuard, MetricsMiddleware, TracingSpanMiddleware, instance_id,
+    HttpMetrics, HttpSnapshotGuard, MetricsMiddleware, TracingSpanMiddleware,
 };
 use sea_orm::ConnectionTrait;
 use service::AppService;