From DNs to User names only: collect cases, think about solution

[fstagni]

(from discussion happening in https://indico.cern.ch/event/893140/)

DNs will not be considered anyone the way for identifying users. Some DNs are hardcoded (TS, Pilot, etc. ) so they would need to be migrated to users IDs, maybe with a one-off script, if they are in the DB.
The code should be anyway backward compatible, at least for one release.

[andresailer]

The SandboxMetadataDB sb_Owners table also stores OwnerDN for some reason

[fstagni]

• ReqDB stores OwnerDN instead of user name. This of course has an impact on several DMS operations (and Transformation.RequestTaskAgent`)
• JobDB.Jobs has both Owner and OwnerDN for whatever reason (?)