Fix: Calico FELIX_IPTABLESBACKEND issue in Redhat Linux 8.x

From official docs says:

FELIX_IPTABLESBACKEND This parameter controls which variant of iptables binary Felix uses. Set this to Auto for auto detection of the backend. If a specific backend is needed then use NFT for hosts using a netfilter backend or Legacy for others. [Default: Auto] Legacy, NFT, Auto

On Redhat 8.x, Set this to Auto for auto detection of the backend ,but not work. The Auto detected Legacy instead of NFT

Update calico-node DaemonSet containers command to:

spec:
  revisionHistoryLimit: 10
  selector:
    matchLabels:
      k8s-app: calico-node
  template:
    metadata:
      creationTimestamp: null
      labels:
        k8s-app: calico-node
    spec:
      containers:
      - args:
        - |-
          sed -i '/bird6/ s/^/# /' /etc/rc.local
          if grep -qE '^nf_tables' /proc/modules ; then sed -i '1i export FELIX_IPTABLESBACKEND=NFT' /etc/rc.local; else sed -i '1i export FELIX_IPTABLESBACKEND=Auto' /etc/rc.local; fi
          start_runit
        command:
        - /bin/sh
        - -c
        env:
        ...
        ...

Verify:

$ kubectl logs -n kube-system calico-node-bj4nd  -c calico-node | grep iptablesbackend
2023-07-30 03:01:52.069 [INFO][15] tunnel-ip-allocator/env_var_loader.go 40: Found felix environment variable: "iptablesbackend"="NFT"

that’s all.
refer: https://github.com/projectcalico/calico/issues/7393