temp fix for nil preemptIDs by qm lib

[asm582]

No description provided.

[atantawi]

• allocResponse.GetPreemptedIds() returns a list of consumer IDs that need be preempted for a requesting consumerID to get its quota demand.

• allocResponse.GetConsumerID() returns the requesting consumerID.

• If the list of preempted IDs is empty, I don't understand why would you want to add consumerID to the list of preempted AppWrappers.

[asm582]

• allocResponse.GetPreemptedIds() returns a list of consumer IDs that need be preempted for a requesting consumerID to get its quota demand.
• allocResponse.GetConsumerID() returns the requesting consumerID.
• If the list of preempted IDs is empty, I don't understand why would you want to add consumerID to the list of preempted AppWrappers.

@atantawi Sure, here is a scenario, When the cluster is full of low-priority AWs and when one high-priority AW comes in we see that allocResponse.GetConsumerID() contains the candidate low-priority AW that will be preempted but allocResponse.GetPreemptedIds() is empty which does not cause preemption of low-priority AW

[atantawi]

Thanks for the clarification. I'll examine.

[asm582]

QM manager library has gone through redesign, I am closing this PR

@metalcycling @atantawi