Update HFDSIDList.py with phH7 ttbb 4FS sample DSIDs
This MR adds the missing DSIDS, 603906 (2L PhH7) 603905 (1L PhH7), for ttbb 4FS samples requested in here: https://its.cern.ch/jira/browse/ATLMCPROD-11004
Please if any expert could confirm that this is enough for having the HF_Classification
flags in the derivation I would be grateful