Deleting port without SG needlessly hits redis

[Sourav Banerjee]

If a port is deleted and it has a mac_address or device_id it will be flagged as valid for security group update (see quark.drivers.security_groups). This may not be necessary if the port has no security groups assigned.
Research needs to be done to see if this deletion is necessary for all cases. Consider SGv3 provider SG feature (currently unimplemented) as well.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/540894
Committed: https://git.openstack.org/cgit/openstack/quark/commit/?id=6e9ae2fc1b226298ef22b341322908698609d214
Submitter: Zuul
Branch: master

commit 6e9ae2fc1b226298ef22b341322908698609d214
Author: Sourav Banerjee <email address hidden>
Date: Thu Nov 2 19:52:13 2017 +0530

    Deleting a port without sg does not hit redis

    Introduced a check in security_groups.py which calls delete_vif
    (which in turn hits redis) only if security_groups is present
    in the kwargs passed to the delete_port function.

    Introduced changes in test_unmanaged_driver.py which change
    test_delete_port by explicitly passing a security_group kwarg &
    test_delete_port_redis_is_dead by asserting that delete_vif
    isn't called as there is no security_group kwarg. Added a new
    test case test_delete_port_no_security_group that verifies that
    delete_vif isn't called if no security_group kwarg (or an empty
    list) is passed.

    Change-Id: I00648f6d490e883175d6592ae64e8c742d35a035
    Closes-Bug: #1747417