Remove _create_security_group_rule & _default_security_group

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_rule
	* _default_security_group

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: I18dd2a3d532273c8dfff730b4f13922717c0abf7
1 file changed