Remove hyphen from rand_name calls in scenario tests

data_utils.rand_name() appends randam charactors with a hypen like:

 def rand_name(name=''):
     randbits = str(random.randint(1, 0x7fffffff))
     if name:
         return name + '-' + randbits

So it is not necessary to specify a hypen in caller side.
This patch removes a hypen in scenario tests.

Change-Id: I21f19e27c3081ac35317d9422436bd8062eced2d
diff --git a/tempest/scenario/test_large_ops.py b/tempest/scenario/test_large_ops.py
index 145efe7..0789c21 100644
--- a/tempest/scenario/test_large_ops.py
+++ b/tempest/scenario/test_large_ops.py
@@ -78,7 +78,7 @@
             self.servers_client.wait_for_server_status(server['id'], status)
 
     def nova_boot(self):
-        name = data_utils.rand_name('scenario-server-')
+        name = data_utils.rand_name('scenario-server')
         flavor_id = CONF.compute.flavor_ref
         # Explicitly create secgroup to avoid cleanup at the end of testcases.
         # Since no traffic is tested, we don't need to actually add rules to