Remove tempest-lib exc Frobidden to Unauthorized translation

This commit removes tempest_lib.exceptions.Forbidden to Unauthorized
translation because it is just a workaround. And, also this commit
removes translation of the tempest-lib exceptions that is workaround
method because it doesn't have any translations anymore. This is the one
of the migrating rest client to tempest-lib works.

Change-Id: If9286d0b326198c391596538d12272c560f1e86d
diff --git a/tempest/api/compute/servers/test_server_personality.py b/tempest/api/compute/servers/test_server_personality.py
index 4a28dfb..b08dbf1 100644
--- a/tempest/api/compute/servers/test_server_personality.py
+++ b/tempest/api/compute/servers/test_server_personality.py
@@ -45,7 +45,7 @@
                                 'contents': base64.b64encode(file_contents)})
         # A 403 Forbidden or 413 Overlimit (old behaviour) exception
         # will be raised when out of quota
-        self.assertRaises((lib_exc.Unauthorized, lib_exc.OverLimit),
+        self.assertRaises((lib_exc.Forbidden, lib_exc.OverLimit),
                           self.create_test_server, personality=personality)
 
     @test.attr(type='gate')