feat(pid_longitudinal_controller): suppress rclcpp_warning/error

[takayuki5168]

Description

Suppress the too-frequent MPC's warning which fills the terminal.
Instead, set a diag with a detailed reason, and show it on the terminal once as follows.

Related links

How was this PR tested?

unit test passed perfectly, and psim worked as expected.

Notes for reviewers

None.

Interface changes

None.

Effects on system behavior

None.

[github-actions]

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[codecov]

Codecov Report

Attention: Patch coverage is 40.00000% with 18 lines in your changes missing coverage. Please review.

Project coverage is 29.65%. Comparing base (b4603fd) to head (8291abd).
Report is 42 commits behind head on main.

Files with missing lines	Patch %	Lines
...nal_controller/src/pid_longitudinal_controller.cpp	37.93%	14 Missing and 4 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #9384      +/-   ##
==========================================
- Coverage   29.66%   29.65%   -0.01%     
==========================================
  Files        1338     1338              
  Lines      103204   103228      +24     
  Branches    40216    40239      +23     
==========================================
+ Hits        30611    30617       +6     
- Misses      69638    69654      +16     
- Partials     2955     2957       +2     

Flag	Coverage Δ		*Carryforward flag
differential	32.45% <40.00%> (?)
total	29.65% <ø> (-0.01%)	⬇️	Carriedforward from b4603fd

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