Use/check MC subcampaign metadata

Rather than having to parse AMI tags or (spurious in MC) run number metadata, the MC (sub)campaign is recorded explicitly in metadata now: https://acode-browser1.usatlas.bnl.gov/lxr/source/athena/Tools/Campaigns/python/Utils.py#0017 This appears under TagInfo/mc_campaign.

It seems this is only present from mc23 onwards, so we can't tear out our current AMI tag translation, but we might want to set up already so that we read this for mc23 and perhaps verify -- or just not attempt this by interpreting tags for these newer samples.