kube: clean up PersistentVolumeClaims

There's no difference as far as jsonnet is concerned, but it may confuse newbies, as Service and SimpleIngress use double colon for its top-level kube helpers. This also removes any ambiguity as to whether this is manifested in final JSON. So we can make that a convention.

Change-Id: I01ad4ea63f4d5d8ee6e5d41c79637ba186548c6f
Reviewed-on: https://gerrit.hackerspace.pl/c/hscloud/+/1803
Reviewed-by: q3k <q3k@hackerspace.pl>
diff --git a/devtools/gerrit/kube/gerrit.libsonnet b/devtools/gerrit/kube/gerrit.libsonnet
index 2d10f32..7fb4171 100644
--- a/devtools/gerrit/kube/gerrit.libsonnet
+++ b/devtools/gerrit/kube/gerrit.libsonnet
@@ -141,10 +141,8 @@
     volumes: {
         [name]: kube.PersistentVolumeClaim(gerrit.name(name)) {
             metadata+: gerrit.metadata("storage"),
-            storage: cfg.storageSize[name],
-            spec+: {
-                storageClassName: cfg.storageClassName,
-            },
+            storage:: cfg.storageSize[name],
+            storageClass:: cfg.storageClassName,
         }
         for name in ["etc", "git", "index", "cache", "db"]
     },