Remove unused main args from test nodes

[dancher00]

Fixes #398.

Removes the unused args parameter from both fixture entry points and initializes rclpy without forwarding it.

Tested with compileall. The ROS-specific lint tests could not run locally because the ament_flake8 and ament_pep257 packages are not installed.

[fujitatomoya]

Pulls: #399
Gist: https://gist.githubusercontent.com/fujitatomoya/dc2c70255d1f13d6c4f63b10391c0e9a/raw/077e85bcb37e3c84711464a3d7c8230a91aada88/ros2.repos
BUILD args: --packages-up-to sros2
TEST args: --packages-select sros2
ROS Distro: rolling
Job: ci_launcher
ci_launcher ran: https://ci.ros2.org/job/ci_launcher/20550

• Linux
• Linux-aarch64
• Linux-rhel
• Windows

[sloretz]

Thank you for the PR!

I see one test failure on Windows, but I think that's a known flaky test. Merging.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 88.18%. Comparing base (51cedf6) to head (49c989d).
⚠️ Report is 2 commits behind head on rolling.

Additional details and impacted files

@@           Coverage Diff            @@
##           rolling     #399   +/-   ##
========================================
  Coverage    88.18%   88.18%           
========================================
  Files           18       18           
  Lines          601      601           
  Branches        53       53           
========================================
  Hits           530      530           
  Misses          52       52           
  Partials        19       19           

Flag	Coverage Δ
unittests	88.18% <ø> (ø)

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