Add support download latest index metadata from remote

Signed-off-by: bansvaru <bansvaru@amazon.com>

plugins/repository-s3/src/main/java/org/opensearch/repositories/s3/S3BlobContainer.java

@@ -343,30 +343,25 @@ private static DeleteObjectsRequest bulkDelete(String bucket, List<String> blobs
     }
 
     @Override
-    public void listBlobsByPrefixInSortedOrder(
+    public List<BlobMetadata> listBlobsByPrefixInSortedOrder(
         String blobNamePrefix,
         int limit,
-        BlobNameSortOrder blobNameSortOrder,
-        ActionListener<List<BlobMetadata>> listener
-    ) {
-        // As AWS S3 returns list of keys in Lexicographic order, we don't have to fetch all the keys in order to sort them
-        // We fetch only keys as per the given limit to optimize the fetch. If provided sort order is not Lexicographic,
-        // we fall-back to default implementation of fetching all the keys and sorting them.
+        BlobNameSortOrder blobNameSortOrder
+    )  throws IOException  {
         if (blobNameSortOrder != BlobNameSortOrder.LEXICOGRAPHIC) {
-            super.listBlobsByPrefixInSortedOrder(blobNamePrefix, limit, blobNameSortOrder, listener);
+            return super.listBlobsByPrefixInSortedOrder(blobNamePrefix, limit, blobNameSortOrder);
         } else {
             if (limit < 0) {
                 throw new IllegalArgumentException("limit should not be a negative value");
             }
             String prefix = blobNamePrefix == null ? keyPath : buildKey(blobNamePrefix);
             try (AmazonS3Reference clientReference = blobStore.clientReference()) {
-                List<BlobMetadata> blobs = executeListing(clientReference, listObjectsRequest(prefix, limit), limit).stream()
+                return executeListing(clientReference, listObjectsRequest(prefix, limit), limit).stream()
                     .flatMap(listing -> listing.contents().stream())
                     .map(s3Object -> new PlainBlobMetadata(s3Object.key().substring(keyPath.length()), s3Object.size()))
                     .collect(Collectors.toList());
-                listener.onResponse(blobs.subList(0, Math.min(limit, blobs.size())));
             } catch (final Exception e) {
-                listener.onFailure(new IOException("Exception when listing blobs by prefix [" + prefix + "]", e));
+                throw new IOException("Exception when listing blobs by prefix [" + prefix + "]", e);
             }
         }
     }