Skip floating fields for plain parents

- parent biome lookups read the biome stream directly instead of building the boundary field
- fields are only built where a parent with floating children needs edge distances

core/src/main/java/art/arcane/iris/generation/biome/FloatingIslandBoundarySampler.java

@@ -48,7 +48,7 @@ public final class FloatingIslandBoundarySampler {
     }
 
     public @Nullable IrisBiome parent(int x, int z) {
-        return parentField(x, z, EDGE_TAPER_WIDTH).parent(x, z);
+        return source.sample(x, z);
     }
 
     public double edgeFade(IrisBiome parent, int x, int z) {
@@ -230,10 +230,6 @@ public final class FloatingIslandBoundarySampler {
             build(source);
         }
 
-        private @Nullable IrisBiome parent(int x, int z) {
-            return parents[geometry.index(x - minX, z - minZ)];
-        }
-
         private int edgeDistance(IrisBiome expected, int x, int z) {
             int index = geometry.index(x - minX, z - minZ);
             if (!sameBiome(expected, parents[index]) || !viable[index]) {