Replace usage of ILBFactory with RepoDomainDb in the following related classes:
- CleanTermsIfUnusedJob
- DatabaseInnerTermStoreCleaner
- DatabaseUsageCheckingTermStoreCleaner
Note that DatabaseInnerTermStoreCleaner and DatabaseUsageCheckingTermStoreCleaner are also created and used in the RemoveDeletedItemsFromTermStore maintenance script, but that should be deleted in T283945.