[flatpak-indexer] Use empty storageClassName

The named volumes doesn't have any storage class set, so the storage
class doesn't match. This should fix it.

roles/openshift-apps/flatpak-indexer/templates/storage.yml.j2

@@ -6,6 +6,10 @@ metadata:
 spec:
   accessModes:
     - ReadWriteMany
+  # Set the storageClassName to the empty string, otherwise it
+  # will get the cluster default storageClass and it won't match
+  # the named volume that already exists for us.
+  storageClassName: ""
   resources:
     requests:
       storage: 5Gi
@@ -18,6 +22,10 @@ metadata:
 spec:
   accessModes:
     - ReadWriteOnce
+  # Set the storageClassName to the empty string, otherwise it
+  # will get the cluster default storageClass and it won't match
+  # the named volume that already exists for us.
+  storageClassName: ""
   resources:
     requests:
       storage: 1Gi