Change default value to align with the original react

test=develop

paddle/fluid/framework/details/execution_strategy.h

@@ -25,7 +25,7 @@ struct ExecutionStrategy {
   size_t num_threads_{0};
   bool use_cuda_{true};
   bool allow_op_delay_{false};
-  size_t num_iteration_per_drop_scope_{100};
+  size_t num_iteration_per_drop_scope_{1};
   ExecutorType type_{kDefault};
   bool dry_run_{false};
 };