The Sharding DDL Coordinator offers a facility to trigger a function at the end of every phase. This can be used to determine if the phase should re-executed based on some conditions, but NOT to rollback actions because the mechanism is not fault-tolerant (i.e., in case of any error while this procure is running would cause the entire phase to be re-executed from scratch).

The goal of this ticket is to provide a recoverable infrastructure to run a procedere at the end of each phase, so that this can be possibly used to rollback actions completed in the current phase.