Decal normals causes underlying shadow masks to become visible

When using a Translucent or Modulate blend mode decal, the underlying shadow may become visible with VSMs, RT Shadows, and with the Pathtracer.

When no normal is applied and a sphere is used to test, the shadow is as expected for a spherical surface. If a normal is applied to the decal, the shadow will stair-step. This stair-stepping is consistent with the shadow mask and raycount views of the VSM debug views.

Notably, this occurs with RT shadows on the directional light or when using the pathtraced view mode, and the latter will show a very visibly faceted normal in the shadowed area of the sphere.

• Create a decal material with the normal connected. Any normal should trigger the behaviour, including a constant 0,0,1.
• Create a decal actor with the aforementioned material and place it above a sphere. This is easiest way to visualise the issue.
• Observe: The decal seems to cause what looks like the VSM shadow mask to show when influencing the sphere.
• Expected: A change in shading as the normal changes, but not the breakup in the shadow that is observed. This also creates heavy faceting with the pathtracer that is only observable when a decal with a normal is influencing the sphere.