fix(path_generator): merge waypoint groups with shared overlap interval

[mitukou1109]

Description

⚠️ This PR must be merged at the same time with autowarefoundation/autoware_launch#1576 ⚠️

This PR fixes waypoint grouping in case adjacent waypoint groups share their overlap interval (partly or entirely).

Before:

After:

Related links

Internal: https://star4.slack.com/archives/C0575HP7NJG/p1753246578053939?thread_ts=1753246357.263529&cid=C0575HP7NJG

How was this PR tested?

Psim

Screencast.from.2025.07.25.16.17.46.webm

Notes for reviewers

None.

Interface changes

ROS Parameter Changes

Additions and removals

Change type	Parameter Name	Type	Default Value	Description
Removed	waypoint_group.separation_threshold	double	1.0	Maximum distance at which consecutive waypoints are considered to belong to the same group [m]

Modifications

Version	Parameter Name	Type	Default Value	Description
Old	waypoint_group.interval_margin_ratio	double	10.0	Ratio for determining length of switching section from centerline to waypoints
New	waypoint.connection_gradient_from_centerline	double	10.0	Gradient for connecting centerline and user-defined waypoints

Effects on system behavior

None.

[github-actions]

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[codecov]

Codecov Report

Attention: Patch coverage is 20.00000% with 4 lines in your changes missing coverage. Please review.

Project coverage is 47.75%. Comparing base (4ecfe7b) to head (4481cbd).

Files with missing lines	Patch %	Lines
planning/autoware_path_generator/src/utils.cpp	0.00%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #586      +/-   ##
==========================================
- Coverage   47.78%   47.75%   -0.04%     
==========================================
  Files         313      313              
  Lines       20088    20099      +11     
  Branches     8746     8747       +1     
==========================================
- Hits         9599     9598       -1     
- Misses       9668     9680      +12     
  Partials      821      821              

Flag	Coverage Δ		*Carryforward flag
differential	21.60% <20.00%> (?)
total	47.79% <ø> (+<0.01%)	⬆️	Carriedforward from 4ecfe7b

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

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[mitukou1109]

2025/07/25 https://evaluation.tier4.jp/evaluation/reports/f17f712a-3e2e-5dad-8b15-a5832e9a58b7?project_id=prd_jt