test: Add helpers to fetch active/inactive storage pool by name
    
    Rather than have repetitive code - create/use a couple of helpers:
    
        testStoragePoolObjFindActiveByName
        testStoragePoolObjFindInactiveByName
    
    This will also allow for the reduction of some cleanup path logic.
    
    Signed-off-by: John Ferlan <jferlan@redhat.com>