Revert "Simplify controller manager namespacing (moveit#2210)"

This reverts commit 55df0bc.

The deprecated constructor was being used in the same file
for the exact use case of enabling namespaces that are not
specified by the parameter. There is no replacement for
supporting a dynamic server lookup, however the parameter
logic could still use simplification.

moveit_plugins/moveit_ros_control_interface/src/controller_manager_plugin.cpp

@@ -255,8 +255,7 @@ class Ros2ControlManager : public moveit_controller_manager::MoveItControllerMan
    * \brief Configure interface with namespace
    * @param ns namespace of ros_control node (without /controller_manager/)
    */
-  [[deprecated("Ros2ControlManager constructor with namespace is deprecated. Set namespace via the "
-               "ros_control_namespace parameter.")]] Ros2ControlManager(const std::string& ns)
+  Ros2ControlManager(const std::string& ns)
     : ns_(ns), loader_("moveit_ros_control_interface", "moveit_ros_control_interface::ControllerHandleAllocator")
   {
     RCLCPP_INFO_STREAM(getLogger(), "Started moveit_ros_control_interface::Ros2ControlManager for namespace " << ns_);
@@ -265,12 +264,18 @@ class Ros2ControlManager : public moveit_controller_manager::MoveItControllerMan
   void initialize(const rclcpp::Node::SharedPtr& node) override
   {
     node_ = node;
-    // Set the namespace from the ros_control_namespace parameter, or default to "/"
-    if (!node_->has_parameter("ros_control_namespace"))
+    if (!ns_.empty())
     {
-      ns_ = node_->declare_parameter<std::string>("ros_control_namespace", "/");
+      if (!node_->has_parameter("ros_control_namespace"))
+      {
+        ns_ = node_->declare_parameter<std::string>("ros_control_namespace", "/");
+      }
+      else
+      {
+        node_->get_parameter<std::string>("ros_control_namespace", ns_);
+      }
     }
-    else
+    else if (node->has_parameter("ros_control_namespace"))
     {
       node_->get_parameter<std::string>("ros_control_namespace", ns_);
       RCLCPP_INFO_STREAM(getLogger(), "Namespace for controller manager was specified, namespace: " << ns_);