Add missing tool manager context in ML segmentation

Summary: I forgot two locations in D312 when introducing tool manager contexts.

Test Plan: Manual testing, ToolManagerProvider test wasn't affected.

Reviewers: O1 MITK Reviewer Group I, thomass, floca

Reviewed By: O1 MITK Reviewer Group I, floca

Maniphest Tasks: T27700

Differential Revision: https://phabricator.mitk.org/D397