Adding components in an Actor then undoing them leaves sub-components

Adding components in an Actor then undoing them after an action in the Viewport, leaves sub-components behind.

This is a regression from 4.19.2 (CL-4033788). This issue was reported and tested in 4.20.1 (CL-4233996). It was reproduced in Main 4.21 (CL-4280116)

1. Open the UE4 Editor and create a blank project
2. Create an Actor Blueprint and add it to the Level
3. Select the Actor and add a "Directional Light" component in the details panel.
4. Add a "Point Light" component in the details panel as well
5. Select one of the lights
6. Move the selected light in the Viewport
7. Select "Edit/Undo Move Components" or use Ctrl-Z

Results: The two lights now have "BillboardComponent_1" and "BillboardComponent_2" sub-components visible in the details panel

Expected: The light is moved back to its location without added sub-components