Optimise DecalOverlay (#25266)

ChunkSize is still 32 so doesn't cut down on heaps of decals atm though we avoid passing many decals to drawing with the coordinates bounds check now.

Content.Shared/Decals/DecalGridComponent.cs

@@ -12,7 +12,8 @@ namespace Content.Shared.Decals
     [NetworkedComponent]
     public sealed partial class DecalGridComponent : Component
     {
-        [DataField("chunkCollection", serverOnly: true)]
+        [Access(Other = AccessPermissions.ReadExecute)]
+        [DataField(serverOnly: true)]
         public DecalGridChunkCollection ChunkCollection = new(new ());
 
         /// <summary>
@@ -25,10 +26,6 @@ namespace Content.Shared.Decals
         /// </summary>
         public GameTick ForceTick { get; set; }
 
-        // client-side data. I CBF creating a separate client-side comp for this. The server can survive with some empty dictionaries.
-        public readonly Dictionary<uint, int> DecalZIndexIndex = new();
-        public readonly SortedDictionary<int, SortedDictionary<uint, Decal>> DecalRenderIndex = new();
-
         [DataDefinition]
         [Serializable, NetSerializable]
         public sealed partial class DecalChunk