Shadow casting still considered for performance when light intensity set to 0.0

Shadow casting is still considered when the lighting intensity has been set to 0.

This is a regression in performance from 4.12.5 where a lights intensity that was set to 0 would not be considered, but in 4.13 and higher when the intensity is set to 0 there is not a significant return on performance. When shadow casting is disabled while the light's intensity is set to 0 you will get the FPS back.

Test project is attached that can easily reproduce this:

• Press F to toggle the light intensity to 0 and back.
• Press R to toggle shadow casting on and off.

1. Open the attached project
2. PIE
3. Enter the command Stat FPS
4. Press F to set the light intensity to 0.0
5. Press R to set Shadow Casting OFF.

Regression: Yes

Results: Shadow casting is still considered when lighting intensity has been set to 0.

Expected: Shadow casting should not be a factor when the light's intensity has been set to 0.0.