Description
VNET TC does not perform tear-down properly. Due to this, the tests executed after VNET (without topology re-creation) will fail.

Steps to reproduce the issue:

1. Run FDB TC.

ansible-playbook test_sonic.yml -i inventory --limit <testbed> \
        -e testbed_name=<testbed> \
        -e testbed_type=t0 -e testcase_name=fdb

2. Run VNET TC

ansible-playbook test_sonic.yml -i inventory --limit <testbed> \
        -e testbed_name=<testbed> \
        -e testbed_type=t0 -e testcase_name=vnet_vxlan

3. Run FDB TC again.

Describe the results you received:

1. FDB TC passed
2. VNET TC passed
3. FDB TC failed

Describe the results you expected:

1. FDB TC passed
2. VNET TC passed
3. FDB TC passed

Additional information you deem important:
DUT config before VNET TC exec: cfg-all-after-bgp-tc.txt
DUT config after VNET TC exec: cfg-all-after-vnet-vxlan-tc.txt