Push testgrid images using workload identity

[fejta]

Also get rid of presets (only used in one location)

Need GoogleCloudPlatform/testgrid#82 to merge first
ref #202

[google-oss-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: fejta, Katharine

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[google-oss-robot]

@fejta: Updated the following 2 configmaps:

• config configmap in namespace default at cluster default using the following files:
  • key config.yaml using file prow/config.yaml
• job-config configmap in namespace default at cluster default using the following files:
  • key esp-v2.yaml using file prow/prowjobs/GoogleCloudPlatform/esp-v2/esp-v2.yaml
  • key gcp-oss-test-infra-config.yaml using file prow/prowjobs/GoogleCloudPlatform/oss-test-infra/gcp-oss-test-infra-config.yaml

In response to this:

Also get rid of presets (only used in one location)

Need GoogleCloudPlatform/testgrid#82 to merge first
ref #202

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