Fix a storage leak in parachains db (#5594)

* Fix cleanup of old votes.

* Cleanup.

* Get rid of redundant import

* Tests + logging

* Fix db key name.

* Add some reasoning to batch size.

* Add dispute data to indexed columns

* Fix fmt

* Add helper function.

* Fix typos.

* Update node/core/dispute-coordinator/src/db/v1.rs

Co-authored-by: Andronik <write@reusable.software>

* Update node/core/dispute-coordinator/src/db/v1.rs

Co-authored-by: Andronik <write@reusable.software>

* Add metric for how long cleanup takes.

Co-authored-by: Andronik <write@reusable.software>