Re-applying !500 (merged) after reverting it with !502 (merged)
To add a bit of context: this MR is needed to fix the reference files when running against Gaudi/master, as is the case for all-slots but not lhcb-master-mr builds that use explicitly Gaudi/v36r6. So in order not to break lhcb-master-mr, this cannot be merged until lhcb-master-mr can move to Gaudi/master (requires bring the LHCb/master stack back in synch with Gaudi/master) or until it can move to a new Gaudi tag that includes the merges of 28/7.
The unfortunate side effect is that any further updates of Boole references will have to be done on top of this MR (and also wait to be merged), to avoid conflicts