Enable validation and disable block-migration

On the multinode job we need to enable validation like the base job
and also disable block migration for live migration that we get from
our parent job.

Change-Id: I076527536e19f7fa2c0cd177bebb1df22db51a0a

.zuul.yaml

@@ -133,7 +133,8 @@
       devstack_localrc:
         ENABLE_FILE_INJECTION: false
         ENABLE_VOLUME_MULTIATTACH: true
-        TEMPEST_RUN_VALIDATION: false
+        TEMPEST_RUN_VALIDATION: true
+        USE_BLOCK_MIGRATION_FOR_LIVE_MIGRATION: false
         CINDER_CEPH_UUID: d531d2d4-3937-429c-b0c2-658fe41e82aa
       devstack_plugins:
         devstack-plugin-ceph: https://opendev.org/openstack/devstack-plugin-ceph