If `--es-config FILE` parameter is specified, use DKB ES storage
as a backup metadata source in case that in primary source (Rucio)
information was removed.

Information from Rucio is removed together with the dataset, so if Rucio
says that dataset is deleted (or not found), the stage can query
internat DKB storage (ES) to get missed information. This functionality
is mostly required for "archived" data reprocessing (when we change the
ETL process or recover missed records).

This branch requires the new functionality, added to the pyDKB library.

Configuration parameters, started with '__', won't be logged.

Without it we won't see in the log those parameters that have default values,
if they are missed in the user passed config.

Move metadata "update" with info from ES to a separate function.