fix(traffic_light_occlusion_predictor): fix cppcheck warnings of functionStatic

[taisa1]

Description

This is a fix based on cppcheck warning functionStatic.

perception/autoware_traffic_light_occlusion_predictor/src/occlusion_predictor.hpp:78:8: performance: inconclusive: Technically the member function 'autoware::traffic_light::CloudOcclusionPredictor::sampleTrafficLightRoi' can be static (but you may consider moving to unnamed namespace). [functionStatic]
perception/autoware_traffic_light_occlusion_predictor/src/occlusion_predictor.hpp:83:8: performance: inconclusive: Technically the member function 'autoware::traffic_light::CloudOcclusionPredictor::calcRoiVector3D' can be static (but you may consider moving to unnamed namespace). [functionStatic]

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How was this PR tested?

Only checked if build succeeded.

Notes for reviewers

None.

Interface changes

None.

Effects on system behavior

None.

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 29.28%. Comparing base (2705a63) to head (fb7047b).
Report is 11 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8258      +/-   ##
==========================================
- Coverage   29.29%   29.28%   -0.02%     
==========================================
  Files        1609     1609              
  Lines      119415   119420       +5     
  Branches    51481    51487       +6     
==========================================
- Hits        34988    34969      -19     
- Misses      75118    75168      +50     
+ Partials     9309     9283      -26     

Flag	Coverage Δ		*Carryforward flag
differential	0.00% <ø> (?)
total	29.28% <ø> (-0.02%)	⬇️	Carriedforward from 2705a63

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[miursh]

@taisa1
For my understanding, could you please explain what is the advantages of adding static to the functions?

[taisa1]

@miursh
Adding static keyword makes it clear that the function does not modify the state of the class object.
In terms of performance, I think there is a slight improvement (by reducing overhead) or no difference.

[miursh]

@taisa1
Thanks!
If a function does not modify the class object, I thought using the const modifier would be appropriate.
However, does using static imply that the function neither modifies nor even accesses the class object at all?

[taisa1]

@miursh
Yes, static functions are not bound to any objects, so the static keyword ensures they do not access non-static members (sorry for the insufficient explanation)

[miursh]

Thank you for your explanation.
LGTM