Fix action test failure due to rate after Rolling sync API change (#3852)

Author: SteveMacenski

nav2_util/test/test_actions.cpp

@@ -548,6 +548,5 @@ int main(int argc, char ** argv)
   ::testing::InitGoogleTest(&argc, argv);
   auto result = RUN_ALL_TESTS();
   rclcpp::shutdown();
-  rclcpp::Rate(1).sleep();
   return result;
 }