app/matrix: migrate postgres and data to waw3

The way this was migrated is not to be spoken of.

(hint: it involved downtime, and mounting two volumes at once)

appservice-irc has some storage, we should migrate that to waw3, too. But
it's not as critical.

The new storage (waw3) is _much_ faster.

Change-Id: I4b4bd32e4fedc514753d25bac35d001e8a9c5f00
diff --git a/kube/postgres.libsonnet b/kube/postgres.libsonnet
index 8208662..e89e9db 100644
--- a/kube/postgres.libsonnet
+++ b/kube/postgres.libsonnet
@@ -16,6 +16,8 @@
         username: error "username must be set",
         # not literal, instead ref for env (like { secretKeyRef: ... })
         password: error "password must be set",
+
+        storageSize: "30Gi",
     },
 
     makeName(suffix):: cfg.prefix + suffix,
@@ -36,7 +38,7 @@
             accessModes: [ "ReadWriteOnce" ],
             resources: {
                 requests: {
-                    storage: "30Gi",
+                    storage: cfg.storageSize,
                 },
             },
         },
@@ -74,6 +76,7 @@
             },
         },
     },
+
     svc: kube.Service(postgres.makeName("postgres")) {
         metadata+: postgres.metadata,
         target_pod:: postgres.deployment.spec.template,