fix(ugc): metal look only from the client's material types

LU Toolbox's metallic table also has colors the client's Materials.xml types
shinyPlastic, such as 131, the grey of many baseplates, so whole baseplates went
into S88_Metal_Model. Metal now comes from the Materials.xml types (shinySteel)
and the settings' colors only; the table still gives colors.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

dUgcServer/Bricks/UgcPalette.cpp

@@ -171,10 +171,6 @@ namespace UgcPalette {
 		return Transparent().contains(id);
 	}
 
-	bool IsMetallic(uint32_t id) {
-		return Metallic().contains(id);
-	}
-
 	std::optional<glm::vec3> Glow(uint32_t id) {
 		const auto it = GlowColors().find(id);
 		return it != GlowColors().end() ? std::optional(it->second) : std::nullopt;