MB 22 is no longer needed as an updated proposal MB 25 was executed via the whitelist track.

Cancel an ongoing referendum.

- `origin`: must be the `CancelOrigin`.
- `index`: The index of the referendum to be cancelled.

Emits `Cancelled`.

- Proposal MB 22 is not needed anymore because a new proposal called MB 25 was already approved.
- MB 25 was executed through the whitelist track.
- The details of MB 22 are no longer important because it has been replaced by MB 25.
- The changes made in MB 25 are more relevant now.
- The decision about MB 22 has been finalized.

#28 Cancel MB22