chore(longhorn): Set longhorn registry explicitly

This patch adjust the default registry, that longhorn will use, in order
to reduce the amount of waiting and probing of registries when using
crio.

infrastructure/longhorn/release.yaml

@@ -18,6 +18,9 @@ spec:
     remediation:
       retries: 15
   values:
+    global:
+      cattle:
+        systemDefaultRegistry: docker.io
     persistence:
       defaultClassReplicaCount: 2
   postRenderers: