Make _create_empty_security_group() non-private

_create_empty_security_group() is made public by this
commit as the tempest.scenario.manager interface is
meant to be consumed by tempest plugins.

Implements: blueprint tempest-scenario-manager-stable
Signed-off by: Soniya Vyas<svyas@redhat.com>

Change-Id: I413ec47416d3d5133e5023360156615b8ce27b13
2 files changed