[ros2]: Launch files simplifications

[JafarAbdi]

Depends on: moveit/moveit2#1283 and moveit/moveit_resources#139

[codecov]

Codecov Report

Merging #369 (99a8af5) into ros2 (d6284ea) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             ros2     #369   +/-   ##
=======================================
  Coverage   42.03%   42.03%           
=======================================
  Files          78       78           
  Lines        7767     7767           
=======================================
  Hits         3264     3264           
  Misses       4503     4503           

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[rhaschke]

I prefer to keep the URDF definition explicit.