Add UNSHELVING and RESCUING into IoOPSFilter consideration state

IoOpsFilter will take instance in following state
task_states.RESIZE_MIGRATING, task_states.REBUILDING, task_states.RESIZE_PREP,
task_states.IMAGE_SNAPSHOT, task_states.IMAGE_BACKUP
into consideration ,if the instance on this host exceed the maximum
number of instance allowed to do I/O the scheduler will fail on the host

UNSHELVING and RESCUING are also I/O related so IoOps need to include them

Change-Id: I141470254c824e7e57e6734ae0e016c432b85c00
Closes-Bug: #1295558
Merge "Add UNSHELVING and RESCUING into IoOPSFilter consideration state"