Remove unnecessary secgroup attrs from scenario tests

Nova "create a server" API refers a security group name only in
security group attributes, but current scenario tests pass the
other attributes(rules, tenant_id, description) also.
That will be a problem on Nova v2.1 API because the API denies
unnecessary attributes for strict validation.
This patch removes them.

Change-Id: I764f00fc1e6a5486367a95a44976e41293aa84c0
Merge "Remove unnecessary secgroup attrs from scenario tests"
Merge branch 'master' of https://github.com/openstack/tempest