Source queued messages are no longer loaded into memory during recovery (since they would just be ignored anyway). This dramatically improves the startup time of a channel if there are many source queued messages, and also prevents the likelihood of the server running out of memory.
Issue: MIRTH-3177
The recovery process now marks all recovered messages as processed before flushing out the source queue (if queuing has been disabled).

RecoveryTask no longer returns a list of messages. It was only being used for tests. Moving forward, we should try not to create code that is only used by tests.
Issue: MIRTH-3181