Fix for 3D Tiles Interactivity demo

[lilleyse]

CC #5676

Sort-term fix for the 3D Tiles Interactivity demo.

[cesium-concierge]

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[pjcozzi]

Do any other Sandcastle examples need this?

I suggest parking this PR and then merging only if we are not able to do the real fix in time for 1.37.

[mramato]

Do any other Sandcastle examples need this?

Pretty much everything using 3D Tiles has a problem, both with picking and draw order/translucency. So we definitely need to fix this for real ASAP.

[bagnell]

Closing this in favor of #5770.