fix(behavior_path_planner): fix invalid access for null drivable area bound

[tkimura4]

Description

In generateDrivableArea function, the invalid access for a left/right bound occurs at findNearestSegmentIndexFromLateralDistance when left_bound or right_bound is empty.
I fixed it

Related links

(TIERIV Internal Link: Scenario )

Tests performed

I confirmed that the behavior_path_planner becomes not to die when the above rosbag played.

Notes for reviewers

no

Interface changes

no

Effects on system behavior

The behavior_path_planner becomes not to die when the bounds of drivable area are empty.

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[codecov]

Codecov Report

Patch coverage has no change and project coverage change: -1.07 ⚠️

Comparison is base (add39cb) 15.53% compared to head (a23244e) 14.46%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3758      +/-   ##
==========================================
- Coverage   15.53%   14.46%   -1.07%     
==========================================
  Files        1333     1432      +99     
  Lines       94699   100837    +6138     
  Branches    30060    29771     -289     
==========================================
- Hits        14708    14585     -123     
- Misses      63904    70402    +6498     
+ Partials    16087    15850     -237     

Flag	Coverage Δ		*Carryforward flag
differential	13.26% <0.00%> (?)
total	14.46% <ø> (-1.07%)	⬇️	Carriedforward from 206bc1e

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

Impacted Files	Coverage Δ
planning/behavior_path_planner/src/utils/utils.cpp	16.87% <0.00%> (-0.06%)	⬇️

... and 114 files with indirect coverage changes

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