Live Node Previews are broken with Coordinates higher than UV0

User reporting the Live Node Preview in the Material Editor will return only Black in the Node when using any UV other than UV0.

Also reproduced in Main Promotable-CL-2552010 & Releases/4.8/Promoted-CL-2550455

1. Open QAGame Editor
2. Create a New Material
3. In the New Material, Turn on Live Nodes and Live Update
4. Add a Texture Sample with Texture2D'/Engine/EngineResources/AICON-Green.AICON-Green' assigned
5. Plug in a Texture Coordinate into the UV of the Texture Sample
6. Plug in the RGB OUtput of Texture Coordinate into Base Color
7. In the Texture Coordinate, set the Coordinate INdex to 1

RESULTS: Material Preview is correct, the Live Node displays black.

EXPECTED: Live Node should still display texture.

Edit MattK: we should use UV0 for preview always as the preview mesh wont have multiple uv sets

Non-zero coordinate index causes incorrect rendering of preview nodes in material editor