CLOUDSTACK-7304: Fixed Exception not raised issue in portable IP test cases

Signed-off-by: Santhosh Edukulla <santhosh.edukulla@gmail.com>
CLOUDSTACK-7284: Fixed cleanup issue in test_escalations_snapshots.py
CLOUDSTACK-7284: Fixed VM delete issue, expunge not allowed by user api client
CLOUDSTACK-7284: Fixed cleanup issue in test_escalations_instances.py, VM should be deleted before deleting the network