Cleanup msg_ variable in RT publisher

[christophfroehlich]

No description provided.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 85.26%. Comparing base (c8b85b9) to head (01d7422).

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #423   +/-   ##
=======================================
  Coverage   85.26%   85.26%           
=======================================
  Files          17       17           
  Lines        1391     1391           
  Branches      132      132           
=======================================
  Hits         1186     1186           
  Misses        119      119           
  Partials       86       86           

Flag	Coverage Δ
unittests	85.26% <ø> (ø)

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

Files with missing lines	Coverage Δ
...ools/include/realtime_tools/realtime_publisher.hpp	90.24% <ø> (ø)

... and 1 file with indirect coverage changes

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[mergify]

This pull request is in conflict. Could you fix it @christophfroehlich?