Investigate tempest failures when using security groups

[Bernard Cafarelli]

To fix tempest gates for Rocky, tests were updated to have port security disabled in https://bugs.launchpad.net/networking-sfc/+bug/1783997

But this is a workaround, we should investigate why tests with a wildcard security group stopped working in that cycle.

To reproduce, revert the networking_sfc/tests/tempest_plugin/tests/scenario changes from https://github.com/openstack/networking-sfc/commit/2000d47b57e093f7de844b22ff67555d7933bc55

Possible root causes: changes in security group defaults, switch to ovsfw?

Pasting information from previous bug:
Since around Rocky mid-cycle, the tempest gates always fail on all tests. Sample failure:
http://logs.openstack.org/05/575705/4/check/networking-sfc-tempest-dsvm/fefcd56/

VMs creation looks OK, but the test fails when trying to connect to a VM and run traceroute to the other:
2018-07-23 17:56:56.323 6755 INFO tempest.lib.common.ssh [-] Creating ssh connection to '172.24.5.20:22' as 'cirros' with public key authentication
2018-07-23 17:56:56.333 6755 INFO paramiko.transport [-] Connected (version 2.0, client dropbear_2012.55)
2018-07-23 17:56:56.607 6755 INFO paramiko.transport [-] Authentication (publickey) successful!
2018-07-23 17:56:56.608 6755 INFO tempest.lib.common.ssh [-] ssh connection to cirros@172.24.5.20 successfully created
2018-07-23 18:00:13.667 6755 ERROR tempest.lib.common.utils.linux.remote_client [-] (TestSfc:test_create_port_chain) Executing command on 172.24.5.20 failed. Error: Request timed out
Details: Command: 'set -eu -o pipefail; PATH=$PATH:/sbin; traceroute -n -I 10.1.0.13' executed on host '172.24.5.20'.: TimeoutException: Request timed out

After some digging I suspect some security group issue, as I deployed a master devstack and manually tested SFC, still working fine. But I disable port security in my manual tests
While tempest test is running, I made a quick test and run "openstack port set --disable-port-security --no-security-group" on all ports related to the test.

This allowed traceroute to finally report in:
    traceroute to 10.0.0.5 (10.0.0.5), 30 hops max, 46 byte packets
     1 * * *
     2 * * *
     3 * * *
     4 * * *
     5 * * *
     6 * 10.0.0.5 2.316 ms 1.935 ms

    2018-07-27 15:07:36,557 16774 ERROR [networking_sfc.tests.tempest_plugin.tests.scenario.base] length mismatch:
    [u' 1 * * *', u' 2 * * *', u' 3 * * *', u' 4 * * *', u' 5 * * *']
    vs
    [[u'10.0.0.8']]

The first '* * *' were timeouts until I disabled port security
Also tweaking the code to run with port security disabled, all tests pass