AggregatingMessageHandler#setExpireGroupsUponCompletion(true) blocks invocation Thread with big persistent MessageStore

Especially it causes blocking affect on the application start-up with config:

<aggregator expire-groups-upon-completion="true"
	message-store="persistentMessageStore"/>

As a fix, to schedule a task for expiring MessageGroups.
Similar solution is in the DelayHandler#reschedulePersistedMessages()