🐛 E2E: Propagate clusterctl variables for cluster upgrades

[vknabel]

What this PR does / why we need it:
We'd like to implement E2E tests for our infrastructure provider. In this case using ClusterUpgradeConformanceSpec.

Though in our case the Control Plane IP address is being created from within our testing suite in Go code and therefore cannot be passed to the tests using the E2EConfig or environment variables. Instead we load the config and patch the variables in-memory. Then we call ClusterUpgradeConformanceSpec. Though the clusterctl.ApplyClusterTemplateAndWait currently does not respect these variables and always derives them from the config file itself.

Passing the variables to the clusterctl apply would solve this issue.

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 #

/area e2e-testing

[linux-foundation-easycla]

• ❌ - login: @vknabel / name: Valentin Knabel . The commit (5ed0e13) is not authorized under a signed CLA. Please click here to be authorized. For further assistance with EasyCLA, please submit a support request ticket.

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by:
Once this PR has been reviewed and has the lgtm label, please assign chrischdi for approval. For more information see the Code Review Process.

The full list of commands accepted by this bot can be found here.

Needs approval from an approver in each of these files:

• OWNERS

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]

Hi @vknabel. Thanks for your PR.

I'm waiting for a github.com member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

I understand the commands that are listed here.

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-sigs/prow repository.

[sbueringer]

@vknabel Thx! Please take a look at #12949 (comment)

[vknabel]

@sbueringer thx for having a look.
The CLA agreement is in internal progress at my company. It should be signed on monday.

[sbueringer]

/ok-to-test
/test pull-cluster-api-e2e-main-gke