Fix logic error in informing user about real-time in ros2_control_node (backport #1726)

[mergify]

The logic in informing user about rt capabilities had logic error. User was informed that rt scheduling is set up when in fact is not setup.

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This is an automatic backport of pull request #1726 done by Mergify.

[codecov]

Codecov Report

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

Project coverage is 62.15%. Comparing base (8e33b4e) to head (a60fce7).

Files	Patch %	Lines
controller_manager/src/ros2_control_node.cpp	0.00%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             iron    #1727      +/-   ##
==========================================
- Coverage   62.17%   62.15%   -0.03%     
==========================================
  Files         109      109              
  Lines       12205    12206       +1     
  Branches     8551     8549       -2     
==========================================
- Hits         7589     7587       -2     
- Misses        867      870       +3     
  Partials     3749     3749              

Flag	Coverage Δ
unittests	62.15% <0.00%> (-0.03%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
controller_manager/src/ros2_control_node.cpp	77.41% <0.00%> (-2.59%)	⬇️

... and 1 file with indirect coverage changes