Fix bad logic in Servo twist speed scaling

[sea-bass]

Description

I mistakenly added some logic to the twist mode of MoveIt Servo in #3007 that did not need to be there.

When the speed commands are in real speed units, we should not touch their scaling value as documented!

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

[sea-bass]

Wait no, I read the comment wrong. This is actually fine.

It says:

"Max linear velocity in m/s if using speed units or tracking a pose, else a scaling factor on the unitless commanded velocity. Used for Cartesian and pose tracking commands."

[codecov-commenter]

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Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 45.66%. Comparing base (cd26fc0) to head (dbdecfb).
Report is 1 commits behind head on main.

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Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3225      +/-   ##
==========================================
- Coverage   46.01%   45.66%   -0.34%     
==========================================
  Files         714      714              
  Lines       62317    62290      -27     
  Branches     7530     7527       -3     
==========================================
- Hits        28667    28438     -229     
- Misses      33484    33685     +201     
- Partials      166      167       +1     

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