[Joint State Broadcaster] Move urdf::Model initialization from on_activate to on_configure to enhance real-time performance

[TakashiSato]

This PR aims to enhance real-time performance during the activation of the Joint State Broadcaster, which was introduced in #1233.

The urdf::Model initialization (here), previously executed within the on_activate function, incurred a substantial amount of time, leading to significant jitter in the Controller Manager's real-time loop.

To address this, the initialization of the urdf::Model has been relocated from on_activate to on_configure, as it can be effectively performed beforehand. In my testing environment, this modification has resulted in a remarkable improvement, accelerating the on_activate process by approximately 40 times (reducing the time from 5ms to 0.12ms).

[christophfroehlich]

Makes sense for me, thanks!

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 80.40%. Comparing base (20f6f0b) to head (9d33a34).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1269      +/-   ##
==========================================
- Coverage   80.42%   80.40%   -0.02%     
==========================================
  Files         105      105              
  Lines        9354     9356       +2     
  Branches      818      821       +3     
==========================================
  Hits         7523     7523              
  Misses       1557     1557              
- Partials      274      276       +2     

Flag	Coverage Δ
unittests	80.40% <100.00%> (-0.02%)	⬇️

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

Files	Coverage Δ
..._state_broadcaster/src/joint_state_broadcaster.cpp	86.53% <100.00%> (-0.65%)	⬇️

... and 4 files with indirect coverage changes

[saikishor]

Sure. Makes sense.

Thank you for the PR

[bmagyar]

great catch, thank you!