[fwaas] Remove secgroup creation related methods

As tempest.scenario.manager was announced stable interface in Tempest
27.0.0[1] it can be now reused in plugins.

Replaced methods:
    * _create_security_group
    * _create_empty_security_group
    * _default_security_group (not in tempest anymore)
    * _create_security_group_rule
    * _create_loginable_secgroup_rule

Etherpad concerning this effort:
https://etherpad.opendev.org/p/tempest-scenario-manager-cleanup

[1] https://docs.openstack.org/releasenotes/tempest/v27.0.0.html#release-notes-27-0-0

Change-Id: I82f69070fa7a873bce95ef7fb57341d38b1b829e
2 files changed