Limit MinIO folder depth to 2

Avoids creating tons of intermediate folders thus reduces inode pressure while still on disk splitting objects in 4.000 slots

Author: chibenwa

server/blob/blob-storage-strategy/src/main/java/org/apache/james/server/blob/deduplication/MinIOGenerationAwareBlobId.java

@@ -74,13 +74,11 @@ public BlobId parse(String id) {
         }
 
         private static String injectFoldersInBlobId(String blobIdPart) {
-            int folderDepthToCreate = 4;
+            int folderDepthToCreate = 2;
             if (blobIdPart.length() > folderDepthToCreate) {
                 return blobIdPart.charAt(0) + "/" +
                     blobIdPart.charAt(1) + "/" +
-                    blobIdPart.charAt(2) + "/" +
-                    blobIdPart.charAt(3) + "/" +
-                    blobIdPart.substring(4);
+                    blobIdPart.substring(2);
             }
             return blobIdPart;
         }