improve test integrity with rmw_cyclonedds_cpp. (backport #440)

[mergify]

Description

address https://ci.ros2.org/job/ci_linux/28060/testReport/junit/launch_testing_examples.launch_testing_examples/check_msgs_launch_test/launch_testing_examples_check_msgs_launch_test/

• before

=============================== warnings summary ===============================
test/test_flake8.py: 28 warnings
  Warning: This process (pid=91118) is multi-threaded, use of fork() may lead to deadlocks in the child.

-- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html
=========================== short test summary info ============================
FAILED launch_testing_examples/check_msgs_launch_test.py::launch_testing_examples.check_msgs_launch_test - launch_testing_examples.check_msgs_launch_test.TestFixture.test_check_if_ms...
============= 1 failed, 9 passed, 28 warnings in 72.00s (0:01:11) ==============

• after

============================= 10 passed in 42.48s ==============================
Finished <<< launch_testing_examples [43.1s]

Part of ros2/rmw_cyclonedds#550

Is this user-facing behavior change?

No

Did you use Generative AI?

No

Additional Information

---

This is an automatic backport of pull request #440 done by [Mergify](https://mergify.com).

[fujitatomoya]

Pulls: #441
Gist: https://gist.githubusercontent.com/fujitatomoya/63ddbf1c5a7d2c3535968a277ac2d3da/raw/6e1719ad8c64a04cf06039b0de5efbac8ca9db30/ros2.repos
BUILD args: --packages-above-and-dependencies launch_testing_examples --cmake-args -DRMW_IMPLEMENTATION=rmw_cyclonedds_cpp
TEST args: --packages-above launch_testing_examples
ROS Distro: humble
Job: ci_launcher
ci_launcher ran: https://ci.ros2.org/job/ci_launcher/18552

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

[fujitatomoya]

Pulls: #441
Gist: https://gist.githubusercontent.com/fujitatomoya/0cefefff953956c2c6308bc3818b4247/raw/6e1719ad8c64a04cf06039b0de5efbac8ca9db30/ros2.repos
BUILD args: --packages-above-and-dependencies launch_testing_examples
TEST args: --packages-above launch_testing_examples
ROS Distro: humble
Job: ci_launcher
ci_launcher ran: https://ci.ros2.org/job/ci_launcher/18555

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