Enable isolated networks in tempest.conf

There was an issue with s-rbac and tempest when isolated networks
were enabled in tempest.conf.

This is no longer an issue as test that were failing with
create_isolated_networks=true and s-rbac enabled are now
passing successfully.

Change-Id: Iae8eac5dffe3c5d15e38a6acd69f2bad95f3f238
diff --git a/.zuul.yaml b/.zuul.yaml
index 122297a..8b56037 100644
--- a/.zuul.yaml
+++ b/.zuul.yaml
@@ -66,15 +66,6 @@
               enforce_scope: True
         test-config:
           $TEMPEST_CONFIG:
-            # FIXME(redrobot): Tempest errors out when you try to create a
-            # system-scope admin because of a neutron client issue where a
-            # tenant_id is required.
-            # To work around that issue we disable create_isolate_networks
-            # here, and we also skip a lot of tests that require that feature.
-            # We should be able to re-enable this once Tempest is fixed.
-            # See: https://review.opendev.org/c/openstack/tempest/+/781553
-            auth:
-              create_isolated_networks: False
             barbican_rbac_scope_verification:
               enforce_scope: True