MetaReader for byte-stream: Convert numeric beam type to string
@harkusha discoverd an issue with the meta reader: When reading Bytestream the beamType ended up as a number while for POOL file it is a string ('cosmics' or 'collisions').
With this MR, the beamType number obtained form the eformat data-reader is convertered into the string expected by job-configuration.
Digging into the code, I belive the various fallback options in https://gitlab.cern.ch/atlas/athena/blob/master/Reconstruction/RecExample/RecExConfig/python/AutoConfiguration.py#L355 saved us for the old configuration.
Tagging @dciubota for info.