Log discrepancy when setting MPPI parameters dynamically

[PlatHum]

Bug report

Required Info:

• Operating System:

  • Ubuntu 22.04

• ROS2 Version:

  • Humble

• Version or commit hash:

  • 1.1.16-1jammy.20240830.231501

• DDS implementation:

  • CycloneDDS

Steps to reproduce issue

Using ros2 param set command to set MPPI parameters triggers a NOT FOUND warning, although the command returns 'Set parameter successful'.

## General form:
ros2 param set /{$controller_server_node_name} {$mppi_controller_name}.{$parameter} {$value}

##For example:
ros2 param set /controller_server FollowPathMPPI.AckermannConstraints.min_turning_r 1.0
##or
ros2 param set /controller_server FollowPathMPPI.gamma 1.0
##or
 ros2 param set /controller_server FollowPathMPPI.ConstraintCritic.cost_weight 1.0

Expected behavior

### If parameter exists, is dynamic and changed successfully
##On set parameter terminal:
Set parameter successful
##On controller_server terminal:
[controller_server-28] [WARN] [controller_server]: {$Something that indicates success in changing parameter}
[controller_server-28] [INFO] [controller_server]: Optimizer reset

### If parameter does not exist, or is not dynamic or not changed successfully
##On set parameter terminal:
Setting parameter failed: {$reason_for_failure}
##On controller_server terminal:
[controller_server-28] [WARN] [controller_server]: {$Something that indicates failure in changing parameter}
[controller_server-28] [INFO] [controller_server]: Optimizer reset

Actual behavior

##On set parameter terminal:
Set parameter successful

##On controller_server terminal:
[controller_server-28] [WARN] [controller_server]: Parameter FollowPathMPPI.AckermannConstraints.min_turning_r not found
[controller_server-28] [INFO] [controller_server]: Optimizer reset

Additional information

Seems like parameters_handler always returns success even though a parameter might not be found.

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