[Eloquent backport] stop using constructors deprecated in pytest 5.4 (#391) Switch to from_parent (partial #421) avoid deprecation warning, use from_parent (#402)

[sloretz]

Cherry pick of #391 - checking if this fixes #458

Now also includes a cherry-pick of one commit from #421: f1c02f3

Now also includes a cherry-pick of #402

[sloretz]

Linux CI

[sloretz]

Linux CI after adding partial cherry-pick of #421

[sloretz]

Linux CI after adding cherry-pick of #402

[mjcarroll]

Supercedes #447

[sloretz]

CI (build: --packages-up-to launch_testing ros2action test: --packages-select launch_testing ros2action ... picked ros2action since it's one of the packages that also showed this deprecation warning by using launch_testing)

• Linux
• Linux-aarch64
• macOS
• Windows

[sloretz]

CI including ros2/launch_ros#176 ( build: --packages-up-to launch_testing launch_testing_ros ros2action ros2interface ros2lifecycle ros2msg ros2node ros2pkg ros2service ros2srv ros2test ros2topic test: --packages-select launch_testing launch_testing_ros ros2action ros2interface ros2lifecycle ros2msg ros2node ros2pkg ros2service ros2srv ros2test ros2topic ... that's all packages that are failing in the Eloquent nightlies)

• Linux
• Linux-aarch64
• macOS
• Windows

[sloretz]

CI looks ok, I think. There's no good build to compare the arm/OSX/Windows builds to, but none of the test failures appear related to this PR. The linux ones all seem to be an unrelated error: AttributeError: module 'pycodestyle' has no attribute 'break_around_binary_operator', which might have to do with a mismatch in the version of pycodestyle and flake8: https://gitlab.com/pycqa/flake8/-/issues/427 ? There's also a couple pep257 test failures for existing doc strings.