⚠️ Remove v1alpha4 API types

[vincepri]

What type of PR is this?

What this PR does / why we need it:

These APIs have been deprecated in their upstream counterpart, and soon be removed.

Let's remove them in the next version?

/kind api-change

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 #

Special notes for your reviewer:

Please confirm that if this PR changes any image versions, then that's the sole change this PR makes.

TODOs:

• squashed commits
• includes documentation
• adds unit tests

Release note:

Remove v1alpha4 API types

[vincepri]

/hold

for tests / consensus

[cpanato]

thank you @vincepri
/approve
/lgtm

will wait for @richardcase then we can lift the hold

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: cpanato, vincepri

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 [cpanato,vincepri]

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

[damdo]

@vincepri @cpanato The v1alpha3 API got removed by #1115, which just merged. So this PR will need updating in title/release-notes/code to only target v1alpha4.

[k8s-ci-robot]

PR needs rebase.

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/test-infra repository.

[richardcase]

Looks good to me. After the rebase lets get this in

[richardcase]

Seems good to me. After a rebase i think we are good to merge this.

[damdo]

Thanks! I'd rename the commit/PR title to just v1alpha4 API types, as the v1alpha3 were removed in the CAPI 1.6.x bump PR. Then LGTM

[vincepri]

/hold cancel

[k8s-ci-robot]

@vincepri: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-cluster-api-provider-gcp-apidiff	39d3e91	link	false	/test pull-cluster-api-provider-gcp-apidiff

Full PR test history. Your PR dashboard. Please help us cut down on flakes by linking to an open issue when you hit one in your PR.

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/test-infra repository. I understand the commands that are listed here.

[damdo]

Thanks!
/lgtm