cluster: k0: upgrade to ceph 16.2.5

This was fun. See b/6 for a log of how swimmingly this went.

Change-Id: I96c3c18b5d33ef86523b3506f49a390419e9ca7f
diff --git a/cluster/kube/lib/rook.libsonnet b/cluster/kube/lib/rook.libsonnet
index 0e875d7..6646df5 100644
--- a/cluster/kube/lib/rook.libsonnet
+++ b/cluster/kube/lib/rook.libsonnet
@@ -726,8 +726,7 @@
             metadata+: cluster.metadata,
             spec: {
                 cephVersion: {
-                    # https://github.com/rook/rook/issues/2945#issuecomment-483964014
-                    image: "ceph/ceph:v14.2.16",
+                    image: "quay.io/ceph/ceph:v16.2.5",
                     allowUnsupported: true,
                 },
                 dataDirHostPath: if name == "ceph-waw2" then "/var/lib/rook" else "/var/lib/rook-%s" % [name],