Enable tenant isolation to tempest for neutron

This commit re-enables tenant isolation in tempest for neutron. This
is a requirement for running tempest in parallel. This commit depends
on tempest change I7587c85017cca09f7a67eae0670f67b2bceacb60

Fixes bug 1216076

Change-Id: I63a30bacd48cecd110fb90e1fc718249c2b1904b
diff --git a/lib/tempest b/lib/tempest
index bc0b18d..646d42b 100644
--- a/lib/tempest
+++ b/lib/tempest
@@ -230,11 +230,6 @@
 
     # Compute
     iniset $TEMPEST_CONF compute change_password_available False
-    # Note(nati) current tempest don't create network for each tenant
-    # so reuse same tenant for now
-    if is_service_enabled neutron; then
-        TEMPEST_ALLOW_TENANT_ISOLATION=${TEMPEST_ALLOW_TENANT_ISOLATION:-False}
-    fi
     iniset $TEMPEST_CONF compute allow_tenant_isolation ${TEMPEST_ALLOW_TENANT_ISOLATION:-True}
     iniset $TEMPEST_CONF compute ssh_user ${DEFAULT_INSTANCE_USER:-cirros} # DEPRECATED
     iniset $TEMPEST_CONF compute network_for_ssh $PRIVATE_NETWORK_NAME