Debian: enable backports repo

We get Ceph 'nautilus' that way to be in sync with CentOS and Ubuntu.
So far only ceph is taken from backports repo.

Change-Id: I9d13ad8a6a610bcf000d3850b77af80d10d66ba7

docker/base/apt_preferences.debian

@@ -0,0 +1,4 @@
+# We want Ceph/nautilus
+Package: ceph* libceph* librados* librbd* librgw* python3-ceph* python3-rados python3-rbd python3-rgw radosgw
+Pin: version 14.*
+Pin-Priority: 1000

docker/base/sources.list.debian

@@ -4,6 +4,9 @@ deb http://deb.debian.org/debian buster main
 # debian security updates
 deb http://security.debian.org/debian-security buster/updates main
 
+# debian backports
+deb http://deb.debian.org/debian buster-backports main
+
 # Buster - Train repos
 deb http://buster-train.debian.net/debian buster-train-backports main
 deb http://buster-train.debian.net/debian buster-train-backports-nochange main

releasenotes/notes/debian-ceph-nautilus-83fe26e66874045f.yaml

@@ -0,0 +1,4 @@
+---
+upgrade:
+  - |
+    Debian images are using Ceph 14 'nautilus' like other distributions.