Disable opencv and vtk python

Summary: Disable opencv and vtk python. Not needed since we use system python, so opencv and vtk python packages should be installed using a python package manager (e.g. pip)

Test Plan: Should be covered by the current tests. Unfortunately they failed before and they are still failing, but this is probably a different issue. I will open separate tasks for them.

Reviewers: O1 MITK Core, kislinsk

Reviewed By: O1 MITK Core, kislinsk

Subscribers: kislinsk

Maniphest Tasks: T25311

Differential Revision: https://phabricator.mitk.org/D162