Revert "moved central/common-update/yyyymmdd/ to central/common-update/"

This reverts commit a6975d7b7e243dcccc5444f37aaa8c0c83910992.

We do need to maintain a common-update for cases where we need to update the central database without releasing a central crop.
This happens when we need to update stored procs needed by old fieldbook or head to head query.