[x] Remove dispatchChanges maint script
[x] Remove ChangeDispatcher
[x] Remove ChangeDispatchCoordinator
[x] Remove pruneChanges maint script (after 2021-10-07)
[x] Remove ChangePruner
[x] Remove PidLock
[x] Remove dispatchLag and the places where it feeds into maxLag
[x] Remove old statistics API integration
[] Think about making new statistics available via API?
[] Remove onApiMaxLagInfo hook?
[] Replace Special Page -> https://gerrit.wikimedia.org/r/c/mediawiki/extensions/Wikibase/+/724084
[x] Remove all puppet config for old maintenance jobs
[] {T292622}
[] Remove specialized analytics scripts for old dispatching
[] Remove Config related to old change dispatching
* [ ] dispatchLagToMaxLagFactor
* [ ] ... TBA
* {icon exclamation-triangle color=orange} consider keeping `localClientDatabases` as it is also used in the new implementation