World Position Offset invalidates Point Lights Entire Virtual Shadow Map Cache when light frustrum is only overlapping a small portion of the mesh

When adding a spotlight to the scene it does not correctly use cached virtual shadow map pages when the spotlight overlaps a mesh using WPO.

This can be most easily observed by entering 'Cached Page" view mode and moving the spotlight towards and away from the mesh.

1. Create a level using the 'Basic' Map Option
2. Create a mesh that utilizes WPO in its material ( e.g a tree )
3. Create a Spotlight
4. Add the Spotlight and the Mesh to the scene
5. Place the editor into 'Cached Page' visualization mode
6. Move the spotlight to overlap a very small portion of the Mesh
7. Observe the visualization turn blue indicating that the entire spot light is invalidating its page cache.
8. Enable the Virtual Shadow Map Stats overlay using the r.Shadow.Virtual.Stats.Visible 1 console command.
9. Observe all physical pages in the cache being dynamically invalidated.

Expected behavior : only those pages where the shadow is drawn are invalidated.