refactor(behavior_velocity_planner): independent of plugin packages

[takayuki5168]

Description

Currently, due to the node test, the behavior_velocity_planner depends on the plugin packages, which is unexpected because we introduced the ROS2's pluginlib so that the node will node depend on the plugin packages.

Referring to the the structure of the behavior_path_planner's node test, this PR changed the structure of the behavior_velocity_planner's node test.
https://github.com/autowarefoundation/autoware.universe/blob/main/planning/behavior_path_planner/autoware_behavior_path_planner/test/test_autoware_behavior_path_planner_node_interface.cpp

The node test in the plugin packages will be added by the succeeding PRs.

Related links

Parent Issue:

• Link

How was this PR tested?

Notes for reviewers

None.

Interface changes

None.

Effects on system behavior

None.

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[codecov]

Codecov Report

Attention: Patch coverage is 50.00000% with 4 lines in your changes missing coverage. Please review.

Project coverage is 29.72%. Comparing base (421ec7d) to head (90cae7c).
Report is 16 commits behind head on main.

Files with missing lines	Patch %	Lines
...oware_behavior_velocity_planner/src/test_utils.cpp	50.00%	2 Missing and 2 partials ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #9760   +/-   ##
=======================================
  Coverage   29.72%   29.72%           
=======================================
  Files        1451     1461   +10     
  Lines      108839   108938   +99     
  Branches    42741    42775   +34     
=======================================
+ Hits        32348    32381   +33     
- Misses      73313    73377   +64     
- Partials     3178     3180    +2     

Flag	Coverage Δ		*Carryforward flag
differential	14.53% <50.00%> (?)
total	29.72% <ø> (ø)		Carriedforward from 421ec7d

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[takayuki5168]

@soblin
Please review the PR. This change is based on the following TIER IV internal discussion.
https://star4.slack.com/archives/C03QW0GU6P7/p1734997806153399