Unittests: refactor AWS::EC2::SecurityGroup tests
Unittests: refactor AWS::EC2::SecurityGroup tests

Refactor mocks for rule creation into separate helper methods.

Change-Id: Ia32639147f12e2a3026b2d8c3efb499d8cea6765

miguelgrinberg/heat,dragorosson/heat,steveb/heat,dims/heat,cwolferh/heat-scratch,takeshineshiro/heat,takeshineshiro/heat,pratikmallya/heat,gonzolino/heat,pshchelo/heat,cwolferh/heat-scratch,maestro-hybrid-cloud/heat,noironetworks/heat,steveb/heat,rh-s/heat,dims/heat,pratikmallya/heat,jasondunsmore/heat,openstack/heat,jasondunsmore/heat,miguelgrinberg/heat,noironetworks/heat,rdo-management/heat,openstack/heat,srznew/heat,dragorosson/heat,rdo-management/heat,rh-s/heat,cryptickp/heat,gonzolino/heat,pshchelo/heat,srznew/heat,maestro-hybrid-cloud/heat,cryptickp/heat