Disable NEUTRON_ENFORCE_SCOPE at function job

The following devstack change I3361d33885b2e3af7cad0141f9b799b2723ee8a1
may be a root cause for failing functional job. This commit should
verify this.

Change-Id: Ica272a5ce5d20dcb52e8a636849af2d71e15afb2

.zuul.yaml

@@ -9,6 +9,7 @@
       openrc_enable_export: true
       devstack_localrc:
         KEYSTONE_ADMIN_ENDPOINT: true
+        NEUTRON_ENFORCE_SCOPE: false
     irrelevant-files:
       - ^.*\.rst$
       - ^doc/.*$