message: Remove unused variables in Follow Me plugin impl
  Removed unused variables `curr_direction_s` & `new_direction_s` in
  `FollowMeImpl::receive_param_follow_direction()`.
diff: @@ -247,8 +247,6 @@ void FollowMeImpl::receive_param_follow_direction(bool success, int32_t directio
  case 3: new_direction = FollowMe::Config::FollowDirection::FRONT_LEFT; break;
  default: break;
  }
  - auto curr_direction_s = FollowMe::Config::to_str(_config.follow_direction);
  - auto new_direction_s = FollowMe::Config::to_str(new_direction);
  if (success) {
  if (new_direction != FollowMe::Config::FollowDirection::NONE) {
  _config.follow_direction = new_direction;
  