Set correct image rendering mode when applying multilabel colormap
- Check the newly set multilabel lookup table instead of the previous lookup table. This bug was introduced/missed in D172.
- Instead of modifying the level window, use the correct image rendering mode that does not use the level window
Test Plan: Manually tested and went through in debugger
Reviewers: O1 MITK Reviewer Group I, floca
Reviewed By: O1 MITK Reviewer Group I, floca
Subscribers: floca, kalali
Differential Revision: https://phabricator.mitk.org/D480