Change fullstack dhclient lease file to tmp folder
Change fullstack dhclient lease file to tmp folder

Each cases are sharing the common lease path for dhclient,
for instance, in CentOS it is: /var/lib/dhclient/dhclient.leases.
That means all fullstack cases will use this file to store
fake VM's NIC DHCP lease information.

After run several times of fullstack cases, the dhclient will
get failed to set the test fake VM port's IP due to the mess
settings in this file.

This patch sets each fake VM's NIC lease file path to the
tmp folder with it's port id.

This may fix some cases that cannot set the IP addr to the test
device properly via DHCP.

Closes-Bug: #1934646
Change-Id: Ia87fa7c08df473acbcf1600035d99a83ed4b4375

openstack/neutron,mahak/neutron,mahak/neutron,mahak/neutron,openstack/neutron,openstack/neutron