Install gcloud auth plugin in kanister build image

[viveksinghggits]

Change Overview

When running the integration test using make integration-test we are asked to install minio using make install-minio but if our k8s cluster is gke and in the kuebconfig gcloud auth plugin is used, make install-minio fails with below error

Unable to connect to the server: getting credentials: exec: executable gke-gcloud-auth-plugin not found

It looks like you are trying to use a client-go credential plugin that is not installed.

To learn more about this feature, consult the documentation available at:
      https://kubernetes.io/docs/reference/access-authn-authz/authentication/#client-go-credential-plugins

Install gke-gcloud-auth-plugin for use with kubectl by following https://cloud.google.com/kubernetes-engine/docs/how-to/cluster-access-for-kubectl#install_plugin

And this seems to be happening because our build image doesn't have gcloud auth plugin installed. This PR installs that.

Pull request type

Please check the type of change your PR introduces:

• [ ] :construction: Work in Progress
• [ ] :rainbow: Refactoring (no functional changes, no api changes)
• [x] :hamster: Trivial/Minor
• [ ] :bug: Bugfix
• [ ] :sunflower: Feature
• [ ] :world_map: Documentation
• [ ] :robot: Test
• [ ] :building_construction: Build

Issues

• fixes #issue-number

Test Plan

• [x] :muscle: Manual
• [ ] :zap: Unit test
• [ ] :green_heart: E2E