Add wait for async secgroup add to minimum basic scenario

Security group add actions are asynchronous so we can't assume that
the security will be available immediately to ssh into the server.
This commit fixes the issue by adding a wait for the secgroup to show
up in the server before we move on.

Fixes-bug: 1390355
Change-Id: Idd561d77ce2e4b83421bb7bfb6327a6c940b62ed