crdb: replace bc01n03 with dcr01s22, upgrade to v20.2.4

This change reflects the current production state.

Upgrade was done by going through following versions:
19.1.0 -> 19.2.12 -> 20.1.10 -> 20.2.4

Change-Id: I8b33b8116363f1a918423fd18ba3d1b5c910851c
diff --git a/cluster/kube/k0.libsonnet b/cluster/kube/k0.libsonnet
index 4f25887..44f83d0 100644
--- a/cluster/kube/k0.libsonnet
+++ b/cluster/kube/k0.libsonnet
@@ -65,7 +65,7 @@
                     topology: [
                         { name: "bc01n01", node: "bc01n01.hswaw.net" },
                         { name: "bc01n02", node: "bc01n02.hswaw.net" },
-                        { name: "bc01n03", node: "bc01n03.hswaw.net" },
+                        { name: "dcr01s22", node: "dcr01s22.hswaw.net" },
                     ],
                     // Host path on SSD.
                     hostPath: "/var/db/crdb-waw1",