Tasks by Type don't allow selection of labels from parent group

Summary

Currently, the "Tasks by type" chart in the Group-level "Value Stream" analytics only allows the user to specify new series for labels that are defined at the current group level. However, it automatically populates with labels from any part of the Issue/MR's parent hierarchy (non-intuitive and apparently conflicting behavior).

Expected behavior

Users should be able to select/deselect labels from the current group or any parent group in the chart series selection dropdown.