Set cgpupns mode to host explicitly

Docker uses cgpupns mode host with cgroupv1, in 22.04 ubuntu
cgroupv2 is default and cgroupns is switched to private which
prevents from calling cgexec and move process out of cgroup
which we use in libvirt.

Related-Prod: PRODX-3456
Change-Id: I93f5f08dde954f0a4010c396b61f2692e15a5bbc
diff --git a/de/heat-templates/scripts/instance_boot.sh b/de/heat-templates/scripts/instance_boot.sh
index 69e903a..3c3431e 100644
--- a/de/heat-templates/scripts/instance_boot.sh
+++ b/de/heat-templates/scripts/instance_boot.sh
@@ -298,6 +298,7 @@
     mkdir -p /etc/docker
     cat <<EOF > /etc/docker/daemon.json
 {
+  "default-cgroupns-mode": "host",
   "default-address-pools": [
     { "base": "${DOCKER_DEFAULT_ADDRESS_POOL}", "size": ${DOCKER_DEFAULT_ADDRESS_SIZE} }
   ],