BookkeeperTool cleanup: only write to the output store once
The motivation for this MR was to avoid deleting objects from meta store. Once the infrastructure was written, I migrated all operations to it and the xAOD::CutBookkeeperContainers are only written out once.
This MR also tries to address multiple files open at once (not tested yet).
The infrastructure is also preparing for automatic handling of all weight variations.