Use sources.list.d for Debian with APT

Under debian, /etc/apt/sources.list.d is where the default list files
are stored. We need to also use that to properly re-write them.

Otherwise, we don't properly configure our AFS mirrors.

Change-Id: I1eb3ac19ba7081d3f4fd9b000e266d86449dee0e
Signed-off-by: Paul Belanger <pabelanger@redhat.com>

roles/configure-mirrors/tasks/mirror/Debian.yaml

@@ -7,10 +7,10 @@
     owner: root
     src: "{{ item }}.j2"
   with_items:
-    - etc/apt/default.list
-    - etc/apt/updates.list
-    - etc/apt/backports.list
-    - etc/apt/security.list
+    - etc/apt/sources.list.d/default.list
+    - etc/apt/sources.list.d/updates.list
+    - etc/apt/sources.list.d/backports.list
+    - etc/apt/sources.list.d/security.list
     - etc/apt/apt.conf.d/99unauthenticated
   notify:
     - Update apt cache