Revert "CentralNotice v2.3 DB Schema Updates"

This patch does not let us create a new wiki and its updater part
is severely broken.

This reverts commit e351640be9652b7c4a8c653093a4e2c2e8dbcca6

Change-Id: Ib7ea880cbf6eb8db6be1ff141a96852c5deeef6d