chore(blind_spot): use getOrDeclareParam

[TakaHoribe]

Description

use tier4_autoware_utils::getOrDeclareParameter for the ros parameter to prevent duplicate parameter declaration.

Tests performed

Run psim

Effects on system behavior

None

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[codecov]

Codecov Report

Patch coverage has no change and project coverage change: -0.01% ⚠️

Comparison is base (4003ba4) 15.10% compared to head (4ce1bea) 15.10%.
Report is 7 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4764      +/-   ##
==========================================
- Coverage   15.10%   15.10%   -0.01%     
==========================================
  Files        1563     1563              
  Lines      107967   107948      -19     
  Branches    33150    33143       -7     
==========================================
- Hits        16305    16301       -4     
+ Misses      73890    73873      -17     
- Partials    17772    17774       +2     

Flag	Coverage Δ		*Carryforward flag
differential	15.25% <0.00%> (?)
total	15.10% <ø> (+<0.01%)	⬆️	Carriedforward from 4003ba4

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

Files Changed	Coverage Δ
...n/euclidean_cluster/src/euclidean_cluster_node.cpp	0.00% <ø> (ø)
...er/src/voxel_grid_based_euclidean_cluster_node.cpp	0.00% <ø> (ø)
...clude/behavior_path_planner/marker_utils/utils.hpp	0.00% <ø> (ø)
...ath_planner/src/marker_utils/lane_change/debug.cpp	0.00% <ø> (ø)
...planner/src/scene_module/lane_change/interface.cpp	6.41% <ø> (+0.08%)	⬆️
...th_planner/src/scene_module/lane_change/normal.cpp	4.04% <ø> (+0.04%)	⬆️
...ner/src/utils/path_safety_checker/safety_check.cpp	29.13% <ø> (-1.47%)	⬇️
...ehavior_velocity_blind_spot_module/src/manager.cpp	32.50% <0.00%> (-1.72%)	⬇️
sensing/imu_corrector/src/imu_corrector_core.cpp	0.00% <ø> (ø)

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