Add definitions used to release the E2E base image

[AlanGreene]

Changes

Follow-up to #3284

Add CronJob patch using kustomize and the existing setup for nightly image releases from the tektoncd/plumbing repo.

We disable the CronJob so it doesn't run on a schedule but can be triggered on demand.

/kind misc

Submitter Checklist

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Release Notes

NONE

[briangleeson]

/lgtm

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