Add server name check for multiple creations

As https://developer.openstack.org/api-ref/compute/#create-multiple-servers
the server names become {name}-1, {name}-2, {name}-3 by default.
Then this patch adds the corresponding check on Tempest.
NOTE: This comes from a review If5369bcf4a6f7fc36190e153776e60446eb14040

Change-Id: I2b544d4ccb54cb5e6db71f788926ac13be7a4fe0
1 file changed