Revert biome rework (#38724)

* Revert "Fix world generation (#38713)"

This reverts commit 10fa6ff4af.

* Revert "Biome rework (#37735)"

This reverts commit fe7b96147c.

Content.Shared/Procedural/PostGeneration/BiomeMarkerLayerDunGen.cs

@@ -0,0 +1,19 @@
+using Content.Shared.Random;
+using Robust.Shared.Prototypes;
+
+namespace Content.Shared.Procedural.PostGeneration;
+
+/// <summary>
+/// Spawns the specified marker layer on top of the dungeon rooms.
+/// </summary>
+public sealed partial class BiomeMarkerLayerDunGen : IDunGenLayer
+{
+    /// <summary>
+    /// How many times to spawn marker layers; can duplicate.
+    /// </summary>
+    [DataField]
+    public int Count = 6;
+
+    [DataField(required: true)]
+    public ProtoId<WeightedRandomPrototype> MarkerTemplate;
+}