[TrivialFix] Remove unused statements in compute tests

This patch removes some unused statements in compute tests to make
code clean.

Change-Id: I7114b19716ba59ed72671616e22bcd468e32d55c
diff --git a/tempest/api/compute/security_groups/test_security_group_rules.py b/tempest/api/compute/security_groups/test_security_group_rules.py
index 124db0e..2b5ae48 100644
--- a/tempest/api/compute/security_groups/test_security_group_rules.py
+++ b/tempest/api/compute/security_groups/test_security_group_rules.py
@@ -178,7 +178,7 @@
             ip_protocol=self.ip_protocol,
             from_port=self.from_port,
             to_port=self.to_port,
-            group_id=sg2_id)['security_group_rule']
+            group_id=sg2_id)
 
         # Delete group2
         self.security_groups_client.delete_security_group(sg2_id)
diff --git a/tempest/api/compute/servers/test_server_metadata.py b/tempest/api/compute/servers/test_server_metadata.py
index f77e7d3..fe95018 100644
--- a/tempest/api/compute/servers/test_server_metadata.py
+++ b/tempest/api/compute/servers/test_server_metadata.py
@@ -32,7 +32,7 @@
     def setUp(self):
         super(ServerMetadataTestJSON, self).setUp()
         meta = {'key1': 'value1', 'key2': 'value2'}
-        self.client.set_server_metadata(self.server['id'], meta)['metadata']
+        self.client.set_server_metadata(self.server['id'], meta)
 
     @decorators.idempotent_id('479da087-92b3-4dcf-aeb3-fd293b2d14ce')
     def test_list_server_metadata(self):
@@ -49,8 +49,7 @@
         # The server's metadata should be replaced with the provided values
         # Create a new set of metadata for the server
         req_metadata = {'meta2': 'data2', 'meta3': 'data3'}
-        self.client.set_server_metadata(self.server['id'],
-                                        req_metadata)['metadata']
+        self.client.set_server_metadata(self.server['id'], req_metadata)
 
         # Verify the expected values are correct, and that the
         # previous values have been removed