Fix the example of KubeExecAll kanister function

[viveksinghggits]

Change Overview

The example in the KubeExecAll was incorrect. This corrects that.

Pull request type

Please check the type of change your PR introduces:

• 🚧 Work in Progress
• 🌈 Refactoring (no functional changes, no api changes)
• 🐹 Trivial/Minor
• 🐛 Bugfix
• 🌻 Feature
• 🗺️ Documentation
• 🤖 Test

Issues

• fixes #issue-number

Test Plan

• 💪 Manual
• ⚡ Unit test
• 💚 E2E

Create a blueprint with below manifest and run the action

apiVersion: cr.kanister.io/v1alpha1
kind: Blueprint
metadata:
  name: cassandra-blueprint
actions:
  backup:
    phases:
    - func: KubeExecAll
      name: examplePhase
      args:
        namespace: "{{ .Deployment.Namespace }}"
        pods: "{{ index .Deployment.Pods 0 }} {{ index .Deployment.Pods 1 }}"
        containers: "nginx"
        command:
          - sh
          - -c
          - |
            echo "Example"

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[ankitjain235]

LGTM