Throw a read error and not a generic error when an LHE read fails

Hello,

Not sure how to get this submitted for all the different versions of CMSSW (manually?), but I guess it should be eventually.

When LHE reads fail (which happens a decent bit with xrootd), a generic CMSSW exception is thrown, which causes problems with the job retry mechanism of CRAB3. This fix throws a read error instead, which is on the whitelist of acceptable-to-retry errors.

Thanks!

@bbockelm