Add "create a server" test with server group

When creating a server with the scheduler_hint "group", the server
will be in the group.
This patch adds the test for checking its behavior.

Change-Id: If5701d381198b01c5ee876bb22b14e5d4b967499
Related-Bug: #1306367
Related-Bug: #1298494
Merge "Add "create a server" test with server group"