Enable ssh validation by default

The -ssh job with ssh validation enabled has been quite stable
for a while now [0] so I think it's time to add ssh validation
to the integration gate to prevent regressions from lurking in.

Doing this in devstack ensures that the change only affects
master as we didn't test ssh validation on on stable branches.

[0] http://status.openstack.org/openstack-health/#/g/build_name/gate-tempest-dsvm-neutron-full-ssh?duration=P3M

Change-Id: I187e560911f5d5d482eb7959e5174068c4c9a801
diff --git a/lib/tempest b/lib/tempest
index cf7eb6f..1640f2c 100644
--- a/lib/tempest
+++ b/lib/tempest
@@ -425,7 +425,7 @@
         TEMPEST_SSH_NETWORK_NAME=$PHYSICAL_NETWORK
     fi
     # Validation
-    iniset $TEMPEST_CONFIG validation run_validation ${TEMPEST_RUN_VALIDATION:-False}
+    iniset $TEMPEST_CONFIG validation run_validation ${TEMPEST_RUN_VALIDATION:-True}
     iniset $TEMPEST_CONFIG validation ip_version_for_ssh 4
     iniset $TEMPEST_CONFIG validation ssh_timeout $BUILD_TIMEOUT
     iniset $TEMPEST_CONFIG validation image_ssh_user ${DEFAULT_INSTANCE_USER:-cirros}