Fix undo remove last child

[AlexVelezLl]

Summary

Description of the change(s) you made

When removing the last child of a folder, the folder was left without nodes, and within the undo transaction there was a resource.where() filter to find the siblings of the recovered node, but as it did not find siblings, it was making an API call, which caused the transaction to end before the api call returned, while there were still operations to be done within the transaction.

This PR just relocates the siblings query so that it is done before the transaction.

Manual verification steps performed

1. verified that removing the last child and then redoing it now worked correctly.
2. verified that the redo of the rest of the operations keep working correctly.

Screenshots (if applicable)

Compartir.pantalla.-.2024-07-24.09_11_14.mp4

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Reviewer guidance

How can a reviewer test these changes?

1. Remove the last node of a channel/folder
2. Wait a couple of seconds for the change to be replicated in IndexedDB
3. Redo de operation

References

Closes #4468

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Reviewer's Checklist

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• Automated test coverage is satisfactory
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[akolson]

Hi @AlexVelezLl!. Although the fix seems to work sometimes, the bug can still be reproduced.

Screen.Recording.2024-07-29.at.14.43.58.mov

[akolson]

@AlexVelezLl, if its useful, I picked up this in the terminal!

[2024-07-29 11:45:35,430: ERROR/ForkPoolWorker-1] A node may not be made a sibling of itself.
Traceback (most recent call last):
  File ".../studio/contentcuration/contentcuration/viewsets/sync/base.py", line 118, in apply_changes
    errors = event_handler([change.serialize_to_change_dict()])
  File ".../studio/contentcuration/contentcuration/viewsets/contentnode.py", line 880, in move_from_changes
    move_error = self.move(
  File ".../studio/contentcuration/contentcuration/viewsets/contentnode.py", line 898, in move
    contentnode.move_to(
  File ".../studio/contentcuration/contentcuration/models.py", line 1872, in move_to
    super(ContentNode, self).move_to(target, *args, **kwargs)
  File ".../.pyenv/versions/3.9.13/envs/studio-py3.9.13/lib/python3.9/site-packages/mptt/models.py", line 851, in move_to
    self._tree_manager.move_node(self, target, position)
  File ".../studio/contentcuration/contentcuration/db/models/manager.py", line 229, in move_node
    self._move_node(node, target, position=position)
  File ".../.pyenv/versions/3.9.13/envs/studio-py3.9.13/lib/python3.9/site-packages/mptt/managers.py", line 44, in wrapped
    return method(self, *args, **kwargs)
  File ".../.pyenv/versions/3.9.13/envs/studio-py3.9.13/lib/python3.9/site-packages/mptt/managers.py", line 577, in _move_node
    self._move_child_node(node, target, position)
  File ".../.pyenv/versions/3.9.13/envs/studio-py3.9.13/lib/python3.9/site-packages/mptt/managers.py", line 1067, in _move_child_node
    self._move_child_within_tree(node, target, position)
  File ".../.pyenv/versions/3.9.13/envs/studio-py3.9.13/lib/python3.9/site-packages/mptt/managers.py", line 1154, in _move_child_within_tree
    raise InvalidMove(_("A node may not be made a sibling of itself."))
mptt.exceptions.InvalidMove: A node may not be made a sibling of itself.

[rtibbles]

The code changes here make sense to me, as they mostly amount to never including the node itself among its own siblings, which seems semantically correct!

If @akolson can confirm he is no long replicating the error he saw, then we should be good to merge.

[akolson]

I can confirm that the issue has now been fully resolved. Manual QA checks out. Thanks @AlexVelezLl 🚀 . cc @rtibbles