Drop debian 13 docker support (#13499)

Debian 13 eliminated apt-key needed to add docker repository.
It needs some work to be supported again.

.gitlab-ci/kubevirt.yml

@@ -142,7 +142,6 @@ pr_extended:
           - almalinux9-calico
           - almalinux9-calico-remove-node
           - almalinux9-docker
-          - debian13-docker
           - debian12-calico
           - debian12-docker
           - debian13-calico

docs/developers/ci.md

@@ -47,7 +47,7 @@ ubuntu26 |  :x: | :x: | :x: | :x: | :x: | :x: |
 almalinux9 |  :white_check_mark: | :x: | :x: | :x: | :x: | :x: |
 amazon |  :x: | :x: | :x: | :x: | :x: | :x: |
 debian12 |  :white_check_mark: | :x: | :x: | :x: | :x: | :x: |
-debian13 |  :white_check_mark: | :x: | :x: | :x: | :x: | :x: |
+debian13 |  :x: | :x: | :x: | :x: | :x: | :x: |
 fedora43 |  :white_check_mark: | :x: | :x: | :x: | :x: | :x: |
 fedora44 |  :x: | :x: | :x: | :x: | :x: | :x: |
 flatcar4081 |  :x: | :x: | :x: | :x: | :x: | :x: |

tests/files/debian13-docker.yml

@@ -1,8 +0,0 @@
----
-# Instance settings
-cloud_image: debian-13
-
-# Use docker
-container_manager: docker
-etcd_deployment_type: docker
-resolvconf_mode: docker_dns