Update PyTest and custom plugins

[Kadino]

Is your feature request related to a problem? Please describe.
A recent open source maintenance issue with the atomicwrites library has forced PyTest to remove it as a dependency: pytest-dev/pytest#10115

Breakage to O3DE's installation mechanism has been patched via #10586 however it would still be appropriate to update PyTest and to reduce dependency on atomicwrites.

Describe the solution you'd like
PyTest is updated to the latest version, along with any required updates to O3DE's custom plugins and configuration files. Remove any dependencies no longer required by pytest, such as the module 'py'

Describe alternatives you've considered
N/A

Additional context
Pytest version is managed by https://github.com/o3de/o3de/blob/development/python/requirements.txt
Plugins exist in https://github.com/o3de/o3de/tree/development/Tools/LyTestTools
Configuration files include https://github.com/o3de/o3de/search?l=INI&q=pytest
Changes to PyTest's API may need to be reflected in https://github.com/o3de/o3de/blob/development/cmake/LYTestWrappers.cmake

[Kadino]

Moved to critical as there is also a security flaw which depends on this change.

[Kadino]

Confirmed custom plugins do in fact fail after upgrading. The majority of failures are emitted from the EditorTest plugin.

[Kadino]

Isolated the single plugin failure to unexpectedly encountering attribute __test__ set explicitly to False for class EditorTest

[Kadino]

There's another underlying failure, which is likely from a previous early-out passing an unexpected node subclass in https://github.com/o3de/o3de/blob/development/Tools/LyTestTools/ly_test_tools/_internal/pytest_plugin/multi_testing.py#L47

[Kadino]

Still don't quite have this narrowed down. Perhaps the pytest_pycollect_makeitem custom registration is being silently aborted by pluggy due to an interface change?