fix(k3s): use DockerProxy mirror for Flux operator manifests

flux/flux-instance.yaml

@@ -7,7 +7,7 @@ spec:
   distribution:
     version: "2.9.2"
     registry: "ghcr.io/fluxcd"
-    artifact: "oci://ghcr.m.daocloud.io/controlplaneio-fluxcd/flux-operator-manifests"
+    artifact: "oci://ghcr.dockerproxy.net/controlplaneio-fluxcd/flux-operator-manifests"
   components:
     - source-controller
     - kustomize-controller