fix(crosswalk): change exceptional handling

[yuki-takagi-66]

Description

Currently, after the backward path go over the default stop line, the crosswalk module do not treat as ego is yielding,
This PR change this behavior with the assumption that default stop pose is null only if the ego has passed the default stop pose.

Related links

#8853

How was this PR tested?

tier4 internal tests

Notes for reviewers

None.

Interface changes

None.

Effects on system behavior

None.

[github-actions]

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 28.46%. Comparing base (d25e9a1) to head (1934ba0).
Report is 12 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8956      +/-   ##
==========================================
- Coverage   28.47%   28.46%   -0.02%     
==========================================
  Files        1314     1319       +5     
  Lines       98279    98330      +51     
  Branches    39961    39963       +2     
==========================================
+ Hits        27985    27986       +1     
- Misses      70166    70216      +50     
  Partials      128      128              

Flag	Coverage Δ		*Carryforward flag
differential	17.76% <ø> (?)
total	28.47% <ø> (ø)		Carriedforward from d25e9a1

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