Cleanup: Add common "create security rule" method

There are many "create security rule" methods in each scenario test,
their behaviors are almost the same. They create security rule which
is loginable/reachable to a server with ssh/ping.
For code-cleanup, this patch adds the method which creates loginable
rules to the specified security group.

Change-Id: I4e2ebd099b7373948c82abf86615a85db055c7c5
Merge "Cleanup: Add common "create security rule" method"