Partially revert commit d29cbd.

MR LHCb/DaVinci!139 introduced some changes for 2018 data-taking that
are not needed in the legacy 2017 branch, specifically the changes for
PersistReco. These PersistReco changes are not needed for 2017 MC
production, and we won't take any more data with 2017-patches, so rather
than port the necessary changes from Phys (LHCb/Phys!233) back to
2017-patches, just don't include the changes.