fix(avoidance): fix target search area width calculation

[satoshi-ota]

Description

🤖 Generated by Copilot at a9b6122

Increase the offset for object separation by path in utils.cpp to prevent collisions with large vehicles.

Related to #4525

---

For now module calculates detection area width from avoidance margin parameter and create detection area along previous output path. But sometimes this logic causes chettering like this ⬇️ .

simplescreenrecorder-2023-08-20_08.04.14.mp4

1. detect object
2. create avoidance path
3. switch the path & update detection area
4. the object is outside of the detection area that is created in step3
5. avoidance maneuver is canceled

Then, I increase detection area margin in order to prevent this chattering.

Tests performed

• PASS TIER IV INTERNAL SCENARIOS

Effects on system behavior

Nothing.

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[codecov]

Codecov Report

Patch coverage: 100.00% and no project coverage change.

Comparison is base (bc86f0e) 14.90% compared to head (7772f3f) 14.90%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4671   +/-   ##
=======================================
  Coverage   14.90%   14.90%           
=======================================
  Files        1548     1548           
  Lines      106793   106794    +1     
  Branches    32682    32682           
=======================================
+ Hits        15917    15918    +1     
  Misses      73552    73552           
  Partials    17324    17324           

Flag	Coverage Δ		*Carryforward flag
differential	13.25% <100.00%> (?)
total	14.90% <ø> (-0.01%)	⬇️	Carriedforward from bc86f0e

*This pull request uses carry forward flags. Click here to find out more.

Files Changed	Coverage Δ
...ehavior_path_planner/src/utils/avoidance/utils.cpp	9.56% <100.00%> (+0.12%)	⬆️

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[kosuke55]

LGTM!