fix(avoidance): fix wrong reason for unavoidable situation

[satoshi-ota]

Description

🤖 Generated by Copilot at e3b0b0b

Refactored the avoidance module in behavior_path_planner to improve performance and readability. Fixed a wrong value for object.reason in avoidance_module.cpp.

---

If the vehicle can't avoid object because of INSUFFICIENT_LATERAL_MARGIN, the avoidance module do nothing in unsafe condition. On the other hand, the reason is TOO_LARGE_JERK, the vehicle stops in front of the object with keeping enough margin to avoid.

Before this PR, sometimes module set wrong unavoidable reason even if there is enough space.

Tests performed

• PASS TIER IV INTERNAL SCENARIOS

Effects on system behavior

Nothing.

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[codecov]

Codecov Report

Attention: 2 lines in your changes are missing coverage. Please review.

Comparison is base (d749a7d) 15.26% compared to head (cc6d66a) 15.25%.
Report is 31 commits behind head on main.

Files	Patch %	Lines
...er/src/scene_module/avoidance/avoidance_module.cpp	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5558      +/-   ##
==========================================
- Coverage   15.26%   15.25%   -0.02%     
==========================================
  Files        1713     1713              
  Lines      118192   119248    +1056     
  Branches    37797    38581     +784     
==========================================
+ Hits        18047    18196     +149     
- Misses      79595    80413     +818     
- Partials    20550    20639      +89     

Flag	Coverage Δ		*Carryforward flag
differential	12.70% <0.00%> (?)
total	15.27% <ø> (+<0.01%)	⬆️	Carriedforward from e3b0b0b

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[rej55]

feasible -> infeasible?