MSAA Causes Black Outline with Atmospheric Fog in Forward Shading

MSAA causes black aliased outline with Atmospheric Fog with Forward Shading enabled. This does not occur with TAA or FXAA. Also does not occur if there is a sky sphere present.

Found in 4.19 CL# 4033788, 4.20 CL# 4369336, 4.21 CL# 4404204

1. Open the Editor
2. Enable Forward Shading and set anti-aliasing to MSAA
3. Restart the Editor and create a blank level
4. Place atmospheric fog, a light, and cube into the level\

Results:
The cube will have a black aliased outline 

Expected:
No outline would be present