ReplicaSet generated by Deployment distributes pods to nodes based
on nodes resource usage, which means in some cases the newly created
pods may be assigned to only a few nodes. The requests will go to the
same node if there multiple pods on it and may increase the node
resource usage and overall request latency.
To solve the problem mentioned above, this PR allows users to deploy
the router as DaemonSet so that we can distribute requests across all
nodes for better workload distribution and lower latency.
