Remove redundant / unused QmitkSliceBasedInterpolatorWidget

Summary:
Remove unused QmitkSliceBasedInterpolatorWidget class

The class was used by the MultilabelSegmentationView,
which has been removed.

Test Plan: check CI builds

Reviewers: s349i, O1 MITK Reviewer Group I, kislinsk

Reviewed By: O1 MITK Reviewer Group I, kislinsk

Subscribers: kalali, s349i

Maniphest Tasks: T28669

Differential Revision: https://phabricator.mitk.org/D699