Don't need all the logging for update_action_result

Author: palfrey

nativelink-service/src/ac_server.rs

@@ -201,7 +201,7 @@ impl ActionCache for AcServer {
 
     #[instrument(
         err,
-        ret(level = Level::INFO),
+        ret(level = Level::TRACE),
         level = Level::ERROR,
         skip_all,
         fields(request = ?grpc_request.get_ref())