refactor(behavior_path_planner): refactor lane change turn signal info

[purewater0901]

Description

Clean code and remove unused codes in the lane change turn signal related functions.

Tests performed

PSim.

Effects on system behavior

Not applicable.

Pre-review checklist for the PR author

The PR author must check the checkboxes below when creating the PR.

• I've confirmed the contribution guidelines.
• The PR follows the pull request guidelines.

In-review checklist for the PR reviewers

The PR reviewers must check the checkboxes below before approval.

• The PR follows the pull request guidelines.

Post-review checklist for the PR author

The PR author must check the checkboxes below before merging.

• There are no open discussions or they are tracked via tickets.

After all checkboxes are checked, anyone who has write access can merge the PR.

[zulfaqar-azmi-t4]

Suggested change

	const auto & length_ratio =
	const auto length_ratio =

this returns trivial type, so you dont need &

[purewater0901]

Fixed with previous PR

[codecov]

Codecov Report

Patch and project coverage have no change.

Comparison is base (90683e5) 14.40% compared to head (bf466c4) 14.40%.

Additional details and impacted files

@@           Coverage Diff            @@
##             main    #3985    +/-   ##
========================================
  Coverage   14.40%   14.40%            
========================================
  Files        1456     1456            
  Lines      102760   102751     -9     
  Branches    29783    30189   +406     
========================================
  Hits        14801    14801            
+ Misses      71783    71771    -12     
- Partials    16176    16179     +3     

Flag	Coverage Δ		*Carryforward flag
differential	12.77% <0.00%> (?)
total	14.41% <ø> (+0.01%)	⬆️	Carriedforward from 290bb71

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

Impacted Files	Coverage Δ
...th_planner/scene_module/lane_change/base_class.hpp	9.75% <ø> (ø)
...r_path_planner/scene_module/lane_change/normal.hpp	100.00% <ø> (ø)
...nner/utils/lane_change/lane_change_module_data.hpp	50.00% <ø> (ø)
...or_path_planner/src/behavior_path_planner_node.cpp	18.30% <0.00%> (-0.05%)	⬇️
...th_planner/src/scene_module/lane_change/normal.cpp	3.68% <0.00%> (+0.03%)	⬆️
...avior_path_planner/src/utils/lane_change/utils.cpp	0.88% <ø> (+0.01%)	⬆️

... and 3 files with indirect coverage changes

☔ View full report in Codecov by Sentry.
📢 Do you have feedback about the report comment? Let us know in this issue.