Update model for offline image

* Fix typos for default offline images names
* Update debmirror repos
* Add entropy for aptly container
* Update MAAS configs

Change-Id: I700216f3727023a36e579da08c0f416b67a94cf8
Related-Prod: PROD-32735
diff --git a/defaults/maas.yml b/defaults/maas.yml
index df932c8..db31590 100644
--- a/defaults/maas.yml
+++ b/defaults/maas.yml
@@ -4,14 +4,14 @@
       maas_mirror_image_sections:
         bootloaders:
           keyring: /usr/share/keyrings/ubuntu-cloudimage-keyring.gpg
-          upstream: ${_param:linux_system_repo_url}/maas-ephemeral-v3/
+          upstream: ${_param:linux_system_repo_update_url}/maas-ephemeral-v3/
           local_dir: /srv/http/${_param:mcp_version}/maas-ephemeral-v3/
           count: 1
           # i386 need for pxe
           filters: ['arch~(i386|amd64)', 'os~(grub*|pxelinux*)']
         xenial:
           keyring: /usr/share/keyrings/ubuntu-cloudimage-keyring.gpg
-          upstream: ${_param:linux_system_repo_url}/maas-ephemeral-v3/
+          upstream: ${_param:linux_system_repo_update_url}/maas-ephemeral-v3/
           local_dir: /srv/http/${_param:mcp_version}/maas-ephemeral-v3/
           count: 1
           filters: ['release~(xenial)', 'arch~(amd64)', 'subarch~(generic|hwe-16*|ga-16*)']