Redo history is deleted if the user clicks inside the blueprint graph

Not a regression as it occurs in Release-4.17

1. Open the level blueprint in any project
2. Open the Edit -> Undo History panel
3. Add a couple of nodes to the level blueprint
4. Ctrl-Z to undo adding the nodes
5. Left click in the Blueprint Graph
6. Ctrl-Y to redo adding nodes

Result: Redo history is removed

Expected: Redo history is retained