Add network internal connectivity check to VMs

In test_network_basic_ops.py, _check_network_internal_connectivity
only checks the connectivity to the network port on the network.
While test_connectivity_between_vms_on_different_networks test
case in this test module explicitly wants to check the
connectivity between vms on different network. Add network
internal connectivty check to other VMs on the network.

Change-Id: Iff8e0f2d5db1bf9bc5bf064a0d066835e8a4cdbc
Fixes-Bug: #1561335
1 file changed