fix extra_packages not in released fatimages

eg htop is not in the 2.7 image openhpc-RL9-250925-1639-62d67ae3.

If a site wants to avoid a particular package from appliances_extra_packages_default, they can override appliances_extra_packages_default in their site group_vars

Author: elelaysh

environments/common/inventory/groups

@@ -202,6 +202,10 @@ k3s_agent
 [extra_packages]
 # Hosts to install specified additional packages on
 
+[extra_packages:children]
+# To include extra packages in base image
+fatimage
+
 [dnf_repos:children]
 # Hosts to replace system repos with Pulp repos
 # Roles/groups listed here *always* do installs: