[system] kubeovn: increase limits (#1629)

## What this PR does
Increases kube-ovn-cni limits

### Release note
```release-note
Increased kube-ovn-cni limits so that it is not oomkilled during startup on busy nodes.
```

packages/system/kubeovn/values.yaml

@@ -44,7 +44,7 @@ kube-ovn:
       memory: "50Mi"
     limits:
       cpu: "1000m"
-      memory: "1Gi"
+      memory: "2Gi"
   kube-ovn-pinger:
     requests:
       cpu: "10m"