Get current limited resource:
- When doing RESPECT_PARTITION_EXCLUSIVITY allocation, we will respect
queues' max capacity.
- When doing IGNORE_PARTITION_EXCLUSIVITY allocation, we will not respect
queue's max capacity, queue's max capacity on the partition will be
considered to be 100%. Which is a queue can use all resource in the
partition.
Doing this because: for non-exclusive allocation, we make sure there's
idle resource on the partition, to avoid wastage, such resource will be
leveraged as much as we can, and preemption policy will reclaim it back
when partitoned-resource-request comes back.