Add Assertion to Ensure Retries in S3BlobContainer (#45224)

* We need a `markSupported` input stream to retry uploads
* Relates #45153

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

@@ -99,6 +99,7 @@ class S3BlobContainer extends AbstractBlobContainer {
      */
     @Override
     public void writeBlob(String blobName, InputStream inputStream, long blobSize, boolean failIfAlreadyExists) throws IOException {
+        assert inputStream.markSupported() : "No mark support on inputStream breaks the S3 SDK's ability to retry requests";
         SocketAccess.doPrivilegedIOException(() -> {
             if (blobSize <= blobStore.bufferSizeInBytes()) {
                 executeSingleUpload(blobStore, buildKey(blobName), inputStream, blobSize);