Camera jumps at the end of morphTo3D transition

To reproduce: https://cesiumjs.org/Cesium/Build/Apps/CesiumViewer/
1. click columbus view
2. drag the map to center somewhere in Africa
3. click 3d, observe the smooth transition but with the sudden jump back to US at the end

If it is to center back to US, the rotation should be part of the transition. But I think if the user interacted with the map (with 2), the current center should persist after the morph.

Reproduce the issue in the CesiumViewer at https://cesiumjs.org/Cesium/Build/Apps/CesiumViewer/ using the listed Columbus View, Africa, and 3D steps. Start by tracing the morphTo3D transition and its final camera rotation; done means the user-selected center persists after morphing, or any return to the US is included in the transition.

Written by the indexing model from the issue text.