🐛 Remove `IdentityRef.Kind`

[EmilienM]

What this PR does / why we need it:

Delete the identityRef.Kind field. It was used to specify the kind of the identity provider to use but was actually ignored.

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged): Fixes #1882

TODOs:

• [X] squashed commits
• if necessary:
  • [X] includes documentation
  • [X] adds unit tests

[netlify[bot]]

✅ Deploy Preview for kubernetes-sigs-cluster-api-openstack ready!

Name	Link
🔨 Latest commit	fc810d87a168f165c7a84c138e7f8fc7c0c1f175
🔍 Latest deploy log	https://app.netlify.com/sites/kubernetes-sigs-cluster-api-openstack/deploys/65dc90ac6e64fb0008fbf15b
😎 Deploy Preview	https://deploy-preview-1903--kubernetes-sigs-cluster-api-openstack.netlify.app/print
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[EmilienM]

/cc stephenfin

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: EmilienM, mdbooth

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: - ~~[OWNERS](https://github.com/kubernetes-sigs/cluster-api-provider-openstack/blob/main/OWNERS)~~ [mdbooth] Approvers can indicate their approval by writing `/approve` in a comment Approvers can cancel approval by writing `/approve cancel` in a comment

[EmilienM]

/cc lentzi90

[EmilienM]

/hold cancel I think it's ready.

[mdbooth]

Restoring @lentzi90's lgtm as there were no changes other than the requested nit fix.

/lgtm