Remove unused CONF from limits/identity_client

CONF is not used in limits_client and identity_client, so this
patch removes it.

Change-Id: I4362e8f71c4508bcd481e9840ca8edad637278a4
diff --git a/tempest/services/database/json/limits_client.py b/tempest/services/database/json/limits_client.py
index 4daf028..6168bfd 100644
--- a/tempest/services/database/json/limits_client.py
+++ b/tempest/services/database/json/limits_client.py
@@ -15,11 +15,8 @@
 
 import urllib
 
-from tempest import config
 from tempest_lib.common import rest_client
 
-CONF = config.CONF
-
 
 class DatabaseLimitsClientJSON(rest_client.RestClient):
 
diff --git a/tempest/services/identity/v3/json/identity_client.py b/tempest/services/identity/v3/json/identity_client.py
index f3d9d2d..95c52bf 100644
--- a/tempest/services/identity/v3/json/identity_client.py
+++ b/tempest/services/identity/v3/json/identity_client.py
@@ -17,11 +17,8 @@
 import urllib
 
 from tempest.common import service_client
-from tempest import config
 from tempest.services.identity.v3.json import base
 
-CONF = config.CONF
-
 
 class IdentityV3ClientJSON(base.IdentityV3Client):