nav2_util: break LifecycleServiceClient ctor wait loop on shutdown

LifecycleServiceClient's constructor blocks on wait_for_service() in a
loop. If the rcl context is invalidated mid-construction (e.g. the
process receives SIGINT before the dependent service comes up), both
wait_for_service() and Rate::sleep() return immediately, which spins
the loop tight and prevents the process from exiting.

Surfaced by test_costmap_subscriber_exec: after the gtest binary now
exits in ~50ms (post-PR-#5834 fixes), the launch wrapper SIGINTs a
lifecycle_manager whose constructor was still in this loop, and the
ctest timeout fires while the manager refuses to die.

Add an rclcpp::ok() check to the loop condition so context shutdown
breaks construction cleanly.

Signed-off-by: lotusymt <mengtiy5@uci.edu>

Author: Lotusymt

nav2_util/include/nav2_util/lifecycle_service_client.hpp

@@ -44,9 +44,10 @@ class LifecycleServiceClient
     get_state_(lifecycle_node_name + "/get_state", parent_node,
       true /*creates and spins an internal executor*/)
   {
-    // Block until server is up
+    // Block until server is up, but bail out if the context is shutting down
+    // so we don't spin forever after SIGINT during construction.
     rclcpp::Rate r(20);
-    while (!get_state_.wait_for_service(2s)) {
+    while (rclcpp::ok() && !get_state_.wait_for_service(2s)) {
       RCLCPP_INFO(
         parent_node->get_logger(),
         "Waiting for service %s...", get_state_.getServiceName().c_str());