drop staging from all jobs using k8s-release-pull

[BenTheElder]

FYI @dims @ameukam @upodroid -- at some point we created this in k8s-infra as an alternative to gs://kubernetes-release-pull, but neither are actually needed.

see #18789

these jobs are all optional and I've already tested this sort of change on a number of jobs now

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: BenTheElder

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• config/OWNERS [BenTheElder]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[ameukam]

/lgtm

[k8s-ci-robot]

@BenTheElder: Updated the job-config configmap in namespace default at cluster test-infra-trusted using the following files:

• key 1.27.yaml using file config/jobs/kubernetes/sig-release/release-branch-jobs/1.27.yaml
• key 1.28.yaml using file config/jobs/kubernetes/sig-release/release-branch-jobs/1.28.yaml
• key 1.29.yaml using file config/jobs/kubernetes/sig-release/release-branch-jobs/1.29.yaml
• key sig-storage-gce-config.yaml using file config/jobs/kubernetes/sig-storage/sig-storage-gce-config.yaml
• key coverage.yaml using file config/jobs/kubernetes/sig-testing/coverage.yaml

In response to this:

FYI @dims @ameukam @upodroid -- at some point we created this in k8s-infra as an alternative to gs://kubernetes-release-pull, but neither are actually needed.

see #18789

these jobs are all optional and I've already tested this sort of change on a number of jobs now

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.