Remove deprecated code from sjtc

[urfeex]

The open_loop parameter has been removed upstream (see ros-controls/ros2_controllers#1598), so we'll have to remove it from here, as well.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 1 line in your changes missing coverage. Please review.

Project coverage is 5.06%. Comparing base (1b121b7) to head (3f08b20).
Report is 436 commits behind head on main.

Files with missing lines	Patch %	Lines
...rollers/src/scaled_joint_trajectory_controller.cpp	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##            main   #1362      +/-   ##
========================================
+ Coverage   3.59%   5.06%   +1.47%     
========================================
  Files         13      33      +20     
  Lines        947    3436    +2489     
  Branches     152     424     +272     
========================================
+ Hits          34     174     +140     
- Misses       843    3260    +2417     
+ Partials      70       2      -68     

Flag	Coverage Δ
unittests	5.06% <0.00%> (+1.47%)	⬆️

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