Get MapData from server data storage

The old patch sources the map data, like vanilla 1.21.11, from the
overworld storage. This is no longer the case in 26.1 and hence reading
the map data from the overworld data storage while writing to the server
storage breaks map rendering.

Author: lynxplay

paper-server/patches/sources/net/minecraft/server/level/ServerLevel.java.patch

@@ -968,7 +968,7 @@
      public @Nullable MapItemSavedData getMapData(final MapId id) {
 -        return this.getServer().getDataStorage().get(MapItemSavedData.type(id));
 +        // Paper start - Call missing map initialize event and set id
-+        final SavedDataStorage storage = this.getServer().overworld().getDataStorage();
++        final SavedDataStorage storage = this.getServer().getDataStorage();
 +
 +        final Optional<net.minecraft.world.level.saveddata.SavedData> cacheEntry = storage.cache.get(MapItemSavedData.type(id));
 +        if (cacheEntry == null) { // Cache did not contain, try to load and may init