fix: update map grid cache when editing maps (#2186)

Author: Mighty-Professional

Intersect.Server.Core/Maps/MapGrid.cs

@@ -1,4 +1,4 @@
-using System.Diagnostics.Contracts;
+using System.Diagnostics.Contracts;
 using Intersect.Server.Database;
 
 using Newtonsoft.Json.Linq;
@@ -74,6 +74,7 @@ public MapGrid(Guid startMapId, int index)
                     map.MapGrid = index;
                     map.MapGridX = (int)x;
                     map.MapGridY = (int)y;
+                    map.CachedMapClientPacket = default;
                     mapIds.Remove(mapId);
                     break;
                 }