T30161 Fixe saving of DCM Seg
Summary:
Remove the drop of the first label (background label are not existing anymore).
Also store the label name in the segment label tag.
Test Plan: review and test saving and reloding multi label segs in DCM
Reviewers: O1 MITK Reviewer Group I, kislinsk
Reviewed By: O1 MITK Reviewer Group I, kislinsk
Subscribers: s434n, a178n, kislinsk
Differential Revision: https://phabricator.mitk.org/D852