Do not restart the Kubernetes Pod once containers exited

Use the spec.restartPolicy and set it to Never.

The spec of a Pod has a restartPolicy field with possible values Always, OnFailure, and Never. The default value is Always.
After containers in a Pod exit, the kubelet restarts them with an exponential back-off delay (10s, 20s, 40s, …), that is capped at five minutes.

An example of such container could be this one:

apiVersion: v1
kind: Pod
metadata:
  name: math-pod
spec:
  containers:
  - name: math-add
    image: ubuntu
    command: ['expr', '10', '+', '23' ]
  restartPolicy: Never