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/multus/templates/multus-daemonset.yml.j2

@@ -23,9 +23,7 @@ spec:
       nodeSelector:
         kubernetes.io/arch: amd64
       tolerations:
-      - key: node-role.kubernetes.io/master
-        operator: Exists
-        effect: NoSchedule
+      - operator: Exists
       serviceAccountName: multus
       containers:
       - name: kube-multus