By default pods in Kubernetes can connect to each other. However in
Qinling, each pod should be independent acting as a worker of a function
or running an execution of a function. Disabling the inter-pods traffic
in the namespace used by Qinling would ensure the isolation of each pod.
This commit leverages the NetworkPolicy in Kubernetes[1] to isolate the
pods. So a network solution which supports NetworkPolicy (for example,
cailco) for Kubernetes must be used or there will be no effect.
[1] https://kubernetes.io/docs/concepts/services-networking/network-policies/
Story: 2001585
Task: 6534
Change-Id: I368323410e92cc23c9a7b50e4936c7070cd57ef7
662794bded