fix(adminrpc): pass otel_enabled as defer arg to avoid double-init

When OTLP is enabled, init_tracing_subscriber() must defer so that
init_otlp() is the sole caller of try_init(). Without this, the adminrpc
binary crashes with "global default trace dispatcher already set".

apps/adminrpc/src/main.rs

@@ -15,7 +15,8 @@ use args::Args;
 async fn main() -> anyhow::Result<()> {
     let cfg = AppConfig::load();
     let log_level = cfg.log_level().unwrap_or_else(|_| "info".to_string());
-    observability::init_tracing_subscriber(&log_level, false);
+    let otel_enabled = cfg.otel_enabled().unwrap_or(false);
+    observability::init_tracing_subscriber(&log_level, otel_enabled);
 
     let args = Args::parse();
     let grpc_addr: SocketAddr = args
@@ -34,7 +35,7 @@ async fn main() -> anyhow::Result<()> {
         "Starting admin RPC server"
     );
 
-    let _otel_guard = if cfg.otel_enabled().unwrap_or(false) {
+    let _otel_guard = if otel_enabled {
         let endpoint = cfg
             .otel_endpoint()
             .unwrap_or_else(|_| "http://localhost:4317".to_string());