fix: Move SmootherParams declaration outside smooth_path conditional (ros-navigation#5473) (ros-navigation#5474)

Fixes crash when dynamically changing smooth_path parameter from false to true.
The issue occurred because SmootherParams were only declared when smooth_path
was initially true, causing ParameterModifiedInCallbackException when trying
to declare parameters within the dynamic parameter callback.

Now SmootherParams are always declared, making them available for dynamic
reconfiguration regardless of the initial smooth_path value.

Fixes ros-navigation#5472


(cherry picked from commit 69a60df)

Co-authored-by: Steve Macenski <stevenmacenski@gmail.com>
Co-authored-by: claude[bot] <209825114+claude[bot]@users.noreply.github.com>

Author: 3 people

nav2_smac_planner/src/smac_planner_hybrid.cpp

@@ -237,9 +237,9 @@ void SmacPlannerHybrid::configure(
     _angle_quantizations);
 
   // Initialize path smoother
+  SmootherParams params;
+  params.get(node, name);
   if (smooth_path) {
-    SmootherParams params;
-    params.get(node, name);
     _smoother = std::make_unique<Smoother>(params);
     _smoother->initialize(_minimum_turning_radius_global_coords);
   }

nav2_smac_planner/src/smac_planner_lattice.cpp

@@ -201,9 +201,9 @@ void SmacPlannerLattice::configure(
     _metadata.number_of_headings);
 
   // Initialize path smoother
+  SmootherParams params;
+  params.get(node, name);
   if (smooth_path) {
-    SmootherParams params;
-    params.get(node, name);
     _smoother = std::make_unique<Smoother>(params);
     _smoother->initialize(_metadata.min_turning_radius);
   }