grenade: start from train, disable heat integration tests

- set the starting point as train (to be adapted in the
  backports of this patch);
- heat tests should have been disabled already here;
  they are really flaky, they takes more time and they should be
  tested by heat.

Change-Id: I5571ac5e578f98465737373598b358aa7dab93e0

devstack/upgrade/settings

@@ -7,11 +7,10 @@ devstack_localrc base IMAGE_URLS=\
 http://tarballs.openstack.org/heat-test-image/fedora-heat-test-image.qcow2"
 devstack_localrc base enable_plugin sahara \
                                     https://opendev.org/openstack/sahara \
-                                    stable/rocky
+                                    stable/train
 devstack_localrc base enable_plugin heat \
                                     https://opendev.org/openstack/heat \
-                                    stable/rocky
-devstack_localrc base DEFAULT_IMAGE_NAME="cirros-0.3.5-x86_64-uec"
+                                    stable/train
 devstack_localrc base DEFAULT_IMAGE_NAME="cirros-0.3.5-x86_64-uec"
 
 devstack_localrc target IMAGE_URLS=\

playbooks/sahara-grenade/run.yaml

@@ -29,6 +29,7 @@
           set -x
           cat << 'EOF' >>"/tmp/dg-local.conf"
           [[local|localrc]]
+          RUN_HEAT_INTEGRATION_TESTS=False
           TEMPEST_PLUGINS+=' ../heat-tempest-plugin ../sahara-tests'
           EOF
         executable: /bin/bash
@@ -56,7 +57,6 @@
           export GRENADE_PLUGINRC+=$'\n'"enable_grenade_plugin heat https://opendev.org/openstack/heat"
 
           export DEVSTACK_GATE_NEUTRON=1
-          export RUN_HEAT_INTEGRATION_TESTS=False
           export DEVSTACK_GATE_TEMPEST=1
           export DEVSTACK_GATE_TEMPEST_REGEX="sahara_tempest_plugin.tests.api"
           export DEVSTACK_GATE_GRENADE=pullup