BUG: fix moving volume nodes from test to main scene

In testing the Reporting extension, a bug was found where error messages were
being printed and the volume node had it's IJK to RAS matrix reset to identity.
Removing the nodes from the test scene before adding them to the main scene
seems to have fixed this, all relevant tests are passing now.
This change removes the following error messages:
GetNodeByID: Node is in the scene, but its ID is missing from the NodeIDs cache: vtkMRMLScalarVolumeNode3
ditto for vtkMRMLScalarVolumeDisplayNode2 and vtkMRMLVolumeArchetypeStorageNode2
and fixes the test py_ReportingRoundTripTest

Issue 0003956

git-svn-id: http://svn.slicer.org/Slicer4/trunk@24391 3bd1e089-480b-0410-8dfb-8563597acbee