fix(path_optimizer): remove unnecesary optional (#10181)

Signed-off-by: Takayuki Murooka <takayuki5168@gmail.com>

Author: takayuki5168

planning/autoware_path_optimizer/include/autoware/path_optimizer/mpt_optimizer.hpp

@@ -75,9 +75,9 @@ struct ReferencePoint
   // additional information
   double curvature{0.0};
   double delta_arc_length{0.0};
-  double alpha{0.0};                          // for minimizing lateral error
-  Bounds bounds{};                            // bounds on `pose`
-  std::vector<std::optional<double>> beta{};  // for collision-free constraint
+  double alpha{0.0};           // for minimizing lateral error
+  Bounds bounds{};             // bounds on `pose`
+  std::vector<double> beta{};  // for collision-free constraint
   double normalized_avoidance_cost{0.0};
 
   // bounds and its local pose on each collision-free constraint

planning/autoware_path_optimizer/src/mpt_optimizer.cpp

@@ -1351,7 +1351,7 @@ MPTOptimizer::ConstraintMatrix MPTOptimizer::calcConstraintMatrix(
 
     // calculate C mat and vec
     for (size_t i = 0; i < N_ref; ++i) {
-      const double beta = *ref_points.at(i).beta.at(l_idx);
+      const double beta = ref_points.at(i).beta.at(l_idx);
       const double lon_offset = vehicle_circle_longitudinal_offsets_.at(l_idx);
 
       C_triplet_vec.push_back(Eigen::Triplet<double>(i, i * D_x, 1.0 * std::cos(beta)));