Fix SDFormat generation of pose elements

[azeey]

🦟 Bug fix

Summary

Fixes a bug when generating SDFormat strings for included models with poses that use one of the newly added attributes (//pose[@degrees] and //pose[@rotation_format]). The issues comes from assigning an updated pose form the ECM to a <pose> element without clearing its attributes. For example, here are a couple of pose tags from the original world:

  <pose degrees='true'>1 2 3    90 0 0</pose>
  <pose rotation_format='quat_xyzw'>1 2 3    0 0 0 1</pose>

The generated world will currently have, which are both incorrect.

  <pose degrees='true'>1 2 3 1.5708 -0 0</pose>
  <pose rotation_format='quat_xyzw'>1 2 3 0 -0 0</pose>

After this PR, the output will be

  <pose>1 2 3 1.5708 -0 0</pose>
  <pose>1 2 3 0 -0 0</pose>

Checklist

• Signed all commits for DCO
• Added tests
• Updated documentation (as needed)
• Updated migration guide (as needed)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
• While waiting for a review on your PR, please help review another open pull request to support the maintainers

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[codecov]

Codecov Report

Merging #1069 (1017d49) into main (064dacc) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main    #1069   +/-   ##
=======================================
  Coverage   64.07%   64.07%           
=======================================
  Files         255      255           
  Lines       19958    19960    +2     
=======================================
+ Hits        12788    12790    +2     
  Misses       7170     7170           

Impacted Files	Coverage Δ
src/SdfGenerator.cc	94.87% <100.00%> (+0.06%)	⬆️

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