Support all taints in network plugins manifests (#6208)

flannel, ovn and multus network plugins did not support all taint keys. This
update changes the tolerations to support them all.

According to the documentation:

```
There are two special cases: An empty key with operator Exists matches all keys,
values and effects which means this will tolerate everything. An empty effect matches
all effects with key key.
```

Usage of the empty `key` and `effect` ensures the network plugin daemonset will
be deployed on every nodes (ex: in case of custom taints, or NoExecute effect)

roles/network_plugin/kube-ovn/templates/cni-kube-ovn.yml.j2

@@ -99,7 +99,6 @@ spec:
     spec:
       tolerations:
       - operator: Exists
-        effect: NoSchedule
       priorityClassName: system-cluster-critical
       serviceAccountName: ovn
       hostNetwork: true
@@ -210,8 +209,7 @@ spec:
         type: infra
     spec:
       tolerations:
-        - operator: Exists
-          effect: NoSchedule
+      - operator: Exists
       serviceAccountName: ovn
       hostPID: true
       containers:
@@ -330,4 +328,4 @@ spec:
     app: kube-ovn-cni
   ports:
     - port: 10665
-      name: metrics
+      name: metrics