Fix scenario test fails when port_vnic_type is set

test_preserv_preexisting_port fails when port_vnic_type
is set in create_server method.if port_vnic_type is set,
ports in the passing create_kwargs will be override,
which cause the inconsistence.

Change-Id: I557b888ca0fc3978699d96d1b02bbe60e58f8c2f
Closes-Bug: #1453818
2 files changed