fixed 4d slice issue

[maharshi-gor]

This PR is for the issue #3075

It introduces the fix for when the volume slider is accessed the 3D slices stops working for that specific slice.

Root cause

The display_extent of the slice actor was changed via a partial and was given an initial object. But while accessing the volume we create new actors for that specific volume value. But when we move the slider it access the old objects, hence providing no updates on ui.

Fix

• The partials are moved to a function which is called again when the volume is changed and new actors are created.