Provisioner should ignore unconfirmed disputes (#6294)

* Fix typos

* Filter unconfirmed disputes in provisioner -  random_selection

* Rework dispute coordinator to return `DisputeStatus` with
`ActiveDisputes` message.
* Rework the random_selection implementation of `select_disptues` in
  `provisioner` to return only confirmed disputes.

* Filter unconfirmed disputes in provisioner - prioritized_selection

* Add test for unconfirmed disputes handling

* Fix `dispute-distribution` tests