[JTC] Remove action_msg dependency (backport #1077)

[mergify]

We included a message header from action_msgs, but there is no need for that.
👀 ros-controls/control_msgs#115

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This is an automatic backport of pull request #1077 done by Mergify.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 71.61%. Comparing base (32757e1) to head (d147ee8).

Additional details and impacted files

@@           Coverage Diff           @@
##             iron    #1081   +/-   ##
=======================================
  Coverage   71.61%   71.61%           
=======================================
  Files          40       40           
  Lines        3449     3449           
  Branches     1695     1696    +1     
=======================================
  Hits         2470     2470           
- Misses        676      682    +6     
+ Partials      303      297    -6     

Flag	Coverage Δ
unittests	71.61% <ø> (ø)

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see 1 file with indirect coverage changes