Add pull-kubernetes-e2e-ec2-alpha-features

[esotsal]

This adds pull-kubernetes-e2e-ec2-alpha-features, a duplicate of https://testgrid.k8s.io/amazon-ec2#ci-kubernetes-e2e-ec2-alpha-features to allow troubleshooting issues seen in this pipeline ( i.e. https://github.com/kubernetes/kubernetes/issues/123951 )

/assign @dims

[dims]

@esotsal any jobs after line https://github.com/kubernetes/test-infra/blob/30150e3af57646fc61baee2b8a064c313c6290a3/config/jobs/kubernetes/sig-node/sig-node-presubmit.yaml#L3285 imply that they are running as presubmit in kubernetes-sigs/provider-aws-test-infra repository. So when you added the same repository in extra refs, the CI job is complaining that the implicit repo also is declared again explicitly.

invalid job pull-kubernetes-e2e-ec2-alpha-features on repo kubernetes-sigs/provider-aws-test-infra: the following refs specified more than once: kubernetes-sigs/provider-aws-test-infra

[dims]

/approve /lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: dims, esotsal

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Needs approval from an approver in each of these files: - ~~[config/jobs/kubernetes/sig-node/OWNERS](https://github.com/kubernetes/test-infra/blob/master/config/jobs/kubernetes/sig-node/OWNERS)~~ [dims] Approvers can indicate their approval by writing `/approve` in a comment Approvers can cancel approval by writing `/approve cancel` in a comment

[k8s-ci-robot]

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

• key sig-node-presubmit.yaml using file config/jobs/kubernetes/sig-node/sig-node-presubmit.yaml

In response to [this](https://github.com/kubernetes/test-infra/pull/32766): >This adds pull-kubernetes-e2e-ec2-alpha-features, a duplicate of https://testgrid.k8s.io/amazon-ec2#ci-kubernetes-e2e-ec2-alpha-features to allow troubleshooting issues seen in this pipeline ( i.e. https://github.com/kubernetes/kubernetes/issues/123951 ) > >/assign @dims Instructions for interacting with me using PR comments are available [here](https://git.k8s.io/community/contributors/guide/pull-requests.md). If you have questions or suggestions related to my behavior, please file an issue against the [kubernetes-sigs/prow](https://github.com/kubernetes-sigs/prow/issues/new?title=Prow%20issue:) repository.