Latest staging images being published with the wrong pre-release tag

### What steps did you take and what happened?

Staging images are published after each merge at CAPI with `main` tags and a hashed tag. The images can be seen at https://console.cloud.google.com/gcr/images/k8s-staging-cluster-api/global/cluster-api-controller

Currently the hashed tag has the form `v20230328-v1.4.0-beta.2-131-g022c70b2b` containing `beta.2` instead of `rc.1` which is the latest pre-release tag.

I believe this image is created from the post-submit job at https://github.com/kubernetes/test-infra/blob/e249292bf64b2f35526ca4c762cedd28b47f2ee0/config/jobs/image-pushing/k8s-staging-cluster-api.yaml#LL3C31-L3C31

### What did you expect to happen?

Tag should contain containing `rc.1` instead of `beta2` which is the latest pre-release tag.

### Cluster API version

rc.1

### Kubernetes version

_No response_

### Anything else you would like to add?

I think this is likely down to a regex or git tag command going wrong somwhere - but the versions I've tried so far appear to have worked.

### Label(s) to be applied

/kind bug
One or more /area label. See https://github.com/kubernetes-sigs/cluster-api/labels?q=area for the list of labels.

Start with config/jobs/image-pushing/k8s-staging-cluster-api.yaml and inspect the post-submit job that publishes the staging image. Trace the regex or git tag command used to build the hashed tag, then verify that the generated tag uses rc.1 rather than beta.2.

Written by the indexing model from the issue text.