Allow to skip stop of ovn services

Grenade jobs stop services, check fip connectivity
for a nova server and then upgrade to next release.

But since ovn data plane and db services are stopped along
with other services, fip connectivity fails as a result.

We shouldn't stop these services along with other
neutron services. This patch adds a new variable
"SKIP_STOP_OVN" which can be used by grenade jobs
to skip stop of ovn services.

This will also fix the ovn grenade jobs.

Also source fixup_stuff.sh so function fixup_ovn_centos
is available. It's already sourced in stack.sh but
that's not used in grenade run.

Change-Id: I94818a19f19973779cb2e11753d2881d54dfa3bc

lib/neutron-legacy

@@ -138,6 +138,9 @@ Q_NOTIFY_NOVA_PORT_DATA_CHANGES=${Q_NOTIFY_NOVA_PORT_DATA_CHANGES:-True}
 VIF_PLUGGING_IS_FATAL=${VIF_PLUGGING_IS_FATAL:-True}
 VIF_PLUGGING_TIMEOUT=${VIF_PLUGGING_TIMEOUT:-300}
 
+# Allow to skip stopping of OVN services
+SKIP_STOP_OVN=${SKIP_STOP_OVN:-False}
+
 # The directory which contains files for Q_PLUGIN_EXTRA_CONF_FILES.
 # /etc/neutron is assumed by many of devstack plugins.  Do not change.
 _Q_PLUGIN_EXTRA_CONF_PATH=/etc/neutron
@@ -638,7 +641,7 @@ function stop_mutnauq {
     stop_mutnauq_other
     stop_mutnauq_l2_agent
 
-    if [[ $Q_AGENT == "ovn" ]]; then
+    if [[ $Q_AGENT == "ovn" && $SKIP_STOP_OVN != "True" ]]; then
         stop_ovn
     fi
 }

lib/neutron_plugins/ovn_agent

@@ -395,6 +395,8 @@ function install_ovn {
         sudo mkdir -p $OVS_PREFIX/var/log/ovn
         sudo chown $(whoami) $OVS_PREFIX/var/log/ovn
     else
+        # Load fixup_ovn_centos
+        source ${TOP_DIR}/tools/fixup_stuff.sh
         fixup_ovn_centos
         install_package $(get_packages openvswitch)
         install_package $(get_packages ovn)