Fixed issue with backup delete

1) Updated class level create_backup function to wait for resource delete
2) Switched the wait_for_resource_deletion handler before delete_backup,
   the clean_up function uses list pop() to perform cleanup. The backup
   has to be deleted before the wait_handler is called

Depends-On https://review.opendev.org/c/openstack/tempest/+/781142

https://storyboard.openstack.org/#!/story/2008683

Change-Id: I6ebc6dcb729baa775e36026081cd8bbf0d5c203f
3 files changed