Nuke: Validate write node fix error report - OP-8088

[tokejepsen]

Changelog Description

Report error was not printing the expected values from settings, but instead the values on the write node, leading to confusing messages like:

Traceback (most recent call last):
  File "C:\Users\tokejepsen\AppData\Local\Ynput\AYON\dependency_packages\ayon_2310271602_windows.zip\dependencies\pyblish\plugin.py", line 527, in __explicit_process
    runner(*args)
  File "C:\Users\tokejepsen\OpenPype\openpype\hosts\nuke\plugins\publish\validate_write_nodes.py", line 135, in process
    self._make_error(check)
  File "C:\Users\tokejepsen\OpenPype\openpype\hosts\nuke\plugins\publish\validate_write_nodes.py", line 149, in _make_error
    raise PublishXmlValidationError(
openpype.pipeline.publish.publish_plugins.PublishXmlValidationError: Write node's knobs values are not correct!
Knob 'channels' > Correct: `rgb` > Wrong: `rgb`

This PR changes the error report to:

Traceback (most recent call last):
  File "C:\Users\tokejepsen\AppData\Local\Ynput\AYON\dependency_packages\ayon_2310271602_windows.zip\dependencies\pyblish\plugin.py", line 527, in __explicit_process
    runner(*args)
  File "C:\Users\tokejepsen\OpenPype\openpype\hosts\nuke\plugins\publish\validate_write_nodes.py", line 135, in process
    self._make_error(check)
  File "C:\Users\tokejepsen\OpenPype\openpype\hosts\nuke\plugins\publish\validate_write_nodes.py", line 149, in _make_error
    raise PublishXmlValidationError(
openpype.pipeline.publish.publish_plugins.PublishXmlValidationError: Write node's knobs values are not correct!
Knob 'channels' > Expected: `['rg']` > Current: `rgb`

Testing notes:

1. Setup wrong value in ayon+settings://nuke/imageio/nodes/required_nodes/0/knobs?project=demo_Commercial
2. Publish in Nuke and verify the report mentions the settings values.

[jakubjezek001]

LGTM