Manage kube-delivery image from training-operator and update it

[rpemsel]

What this PR does / why we need it:

When running an MPI Job kubectl is required to start the mpi binary on the workers. The launcher connects to the workers using kubectl. This kubectl is provided by an init container. That init container provides a very old version of kubectl. Also the image for the init container is not controlled inside the training operator repository. So with the pull request the image is managed within the repository.

Also it uses a 1.27 version of the kubectl that provides the latest features and fixes.

Which issue(s) this PR fixes (optional, in Fixes #<issue number>, #<issue number>, ... format, will close the issue(s) when PR gets merged):
Fixes #1899

Checklist:

• Docs included if any changes are user facing

[terrytangyuan]

/lgtm

[google-oss-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: rpemsel, terrytangyuan

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