fix(planning_evaluator): fix typo (#4405)

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

Author: takayuki5168

evaluator/planning_evaluator/src/metrics/obstacle_metrics.cpp

@@ -64,10 +64,10 @@ Stat<double> calcTimeToCollision(
       const double dt = traj_dist / std::abs(p0.longitudinal_velocity_mps);
       t += dt;
       for (auto obstacle : obstacles.objects) {
-        const double obst_dist =
+        const double obstacle_dist =
           calcDistance2d(p, obstacle.kinematics.initial_pose_with_covariance.pose);
         // TODO(Maxime CLEMENT): take shape into consideration
-        if (obst_dist <= distance_threshold) {
+        if (obstacle_dist <= distance_threshold) {
           stat.add(t);
           break;
         }