Fix H404/405 violations for api tests(3/3)

There is a lot of H404/405 violations in Tempest now, and that leads
difficult to migrate the code to tempest-lib or the other projects'
repos. This patch fixes these violations for api tests of compute.

Change-Id: Id6346f6a4a46dea56319ab482a4f499d0de098f9
diff --git a/tempest/api/compute/admin/test_agents.py b/tempest/api/compute/admin/test_agents.py
index 38f5fb7..d2b3a81 100644
--- a/tempest/api/compute/admin/test_agents.py
+++ b/tempest/api/compute/admin/test_agents.py
@@ -23,9 +23,7 @@
 
 
 class AgentsAdminTestJSON(base.BaseV2ComputeAdminTest):
-    """
-    Tests Agents API
-    """
+    """Tests Agents API"""
 
     @classmethod
     def setup_clients(cls):