@Override
  protected void applyDelete(MessageInfo remoteBlob, RemoteReplicaInfo remoteReplicaInfo) {
    throw new UnsupportedOperationException("applyDelete is unsupported");
  }
This checks for GDPR compliance.
 If a blob has been deleted from remote on-prem servers, it must be absent in local-store
 @param remoteBlob the {@link MessageInfo} that will be transformed into a delete-operation
 @param remoteReplicaInfo The remote replica that is being replicated from
ambry-replication/src/main/java/com/github/ambry/replication/BackupCheckerThread.java