feat(motion_utils, etc): add header argument in convertToTrajectory

[takayuki5168]

Description

Added a header argument with a default value in motion_utils::convertToTrajectory, which is a necessary variable for the visualization in Rviz.
And removed the utility functions to fill in the header of the trajectory which became unnecessary with the upper change in the obstacle_avoidance_planner, path_smoother, path_sampler, and planning_topic_converter packages.

Tests performed

psim

Effects on system behavior

Nothing

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[codecov]

Codecov Report

Attention: 13 lines in your changes are missing coverage. Please review.

Comparison is base (5de111f) 15.23% compared to head (de6176f) 15.23%.

Files	Patch %	Lines
...g/obstacle_avoidance_planner/src/mpt_optimizer.cpp	0.00%	0 Missing and 3 partials ⚠️
planning/obstacle_avoidance_planner/src/node.cpp	33.33%	1 Missing and 1 partial ⚠️
planning/path_smoother/src/elastic_band.cpp	0.00%	0 Missing and 2 partials ⚠️
...anning/path_smoother/src/elastic_band_smoother.cpp	0.00%	1 Missing and 1 partial ⚠️
...g/sampling_based_planner/path_sampler/src/node.cpp	0.00%	2 Missing ⚠️
planning/obstacle_cruise_planner/src/node.cpp	0.00%	0 Missing and 1 partial ⚠️
...lanning_topic_converter/src/path_to_trajectory.cpp	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6021      +/-   ##
==========================================
- Coverage   15.23%   15.23%   -0.01%     
==========================================
  Files        1751     1751              
  Lines      120918   120898      -20     
  Branches    36770    36779       +9     
==========================================
- Hits        18421    18416       -5     
+ Misses      81825    81812      -13     
+ Partials    20672    20670       -2     

Flag	Coverage Δ		*Carryforward flag
differential	18.31% <7.14%> (?)
total	15.23% <ø> (-0.01%)	⬇️	Carriedforward from 5de111f

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