Description:
ChangeQuorum is strictly restricted to databases that use dual region instance configurations. Initiates a background operation to change quorum a database from dual-region mode to single-region mode and vice versa. The returned long-running operation will have a name of the format `projects//instances//databases//operations/` and can be used to track execution of the ChangeQuorum. The metadata field type is ChangeQuorumMetadata. Authorization requires `spanner.databases.changequorum` permission on the resource database.