Javadoc
Check if the allocation of the replica is to be delayed. Compute the delay and if it is delayed, add it to the ignore unassigned list
Note: we only care about replica in delayed allocation, since if we have an unassigned primary it
will anyhow wait to find an existing copy of the shard to be allocated
Note: the other side of the equation is scheduling a reroute in a timely manner, which happens in the RoutingService
PUBLIC FOR TESTS!