Upgrade the net container from Bookworm to Trixie (sonic-net#22995)

Also add a new variable for the Docker registry, since the containers
for the newer Debian versions are mirrored in a different Docker
registry.

Signed-off-by: Saikrishna Arcot <sarcot@microsoft.com>
Co-authored-by: Saikrishna Arcot <sarcot@microsoft.com>

Author: auspham

ansible/roles/vm_set/tasks/add_ceos_list.yml

@@ -109,7 +109,7 @@
   become: yes
   docker_container:
     name: net_{{ vm_set_name }}_{{ vm_name }}
-    image: "{{ docker_registry_host }}/debian:bookworm"
+    image: "{{ debian_docker_registry_host }}/debian:trixie"
     pull: no
     state: started
     restart: no

ansible/vars/docker_registry.yml

@@ -1 +1,2 @@
 docker_registry_host: sonicdev-microsoft.azurecr.io:443
+debian_docker_registry_host: publicmirror.azurecr.io:443