remove intra-process manager impl (#382)

Signed-off-by: Soragna, Alberto <alberto.soragna@gmail.com>

demo_nodes_cpp/src/topics/allocator_tutorial.cpp

@@ -155,10 +155,6 @@ int main(int argc, char ** argv)
   if (intra_process) {
     printf("Intra-process pipeline is ON.\n");
     auto context = rclcpp::contexts::default_context::get_global_default_context();
-    auto ipm_state =
-      std::make_shared<rclcpp::intra_process_manager::IntraProcessManagerImpl<MessageAlloc>>();
-    // Constructs the intra-process manager with a custom allocator.
-    context->get_sub_context<rclcpp::intra_process_manager::IntraProcessManager>(ipm_state);
     auto options = rclcpp::NodeOptions()
       .context(context)
       .use_intra_process_comms(true);