Use attached object colors as is in Rviz plugin (backport #3274)

[mergify]

Description

Fixes #3273. As explained in #3273, there is some weird code from 2013 that messes up the colors of attached objects in rviz, overriding the colors provided via the planning scene interface with potentially out of range values. This removes the erroneous code and just passes the colors as is.

Checklist

• Required by CI: Code is auto formatted using clang-format
• Extend the tutorials / documentation reference
• Document API changes relevant to the user in the MIGRATION.md notes
• Create tests, which fail without this PR reference
• Include a screenshot if changing a GUI
• While waiting for someone to review your request, please help review another open pull request to support the maintainers

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This is an automatic backport of pull request #3274 done by [Mergify](https://mergify.com).

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Codecov Report

Attention: Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.

Project coverage is 51.42%. Comparing base (8d89f73) to head (01416ca).
Report is 1 commits behind head on humble.

Files with missing lines	Patch %	Lines
...gin_render_tools/src/robot_state_visualization.cpp	0.00%	2 Missing ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##           humble    #3277      +/-   ##
==========================================
+ Coverage   51.40%   51.42%   +0.02%     
==========================================
  Files         382      382              
  Lines       31896    31894       -2     
==========================================
+ Hits        16394    16398       +4     
+ Misses      15502    15496       -6     

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