Remove priority field from the APIService manifest to make it compatible with 1.11+ bootstrap clusters

[xmudrii]

What this PR does / why we need it:

As of Kubernetes 1.11, the priority field has been removed from the APIService resource. The priority field have been replaced with groupPriority and versionPriority fields.

More about those fields can be found in godoc comments.

Those fields have been backported to older Kubernetes versions, including 1.10 used by Minikube. Here's a commit that introduced that change: kubernetes/kubernetes@d13ad28

Trying to create a cluster using clusterctl with a bootstrap cluster version 1.11 or newer, results in the following error:

[marko@xmudrii-1 clusterctl (master)]$ go run main.go create cluster --provider digitalocean -c examples/digitalocean/out/cluster.yaml -m examples/digitalocean/out/machines.yaml -p examples/digitalocean/out/provider-components.yaml --cleanup-bootstrap-cluster false --existing-bootstrap-cluster-kubeconfig /var/run/kubernetes/admin.kubeconfig
I0829 12:45:28.516323   13818 clusterdeployer.go:122] Creating bootstrap cluster
I0829 12:45:28.520057   13818 clusterdeployer.go:130] Applying Cluster API stack to bootstrap cluster
I0829 12:45:28.520078   13818 clusterdeployer.go:313] Applying Cluster API APIServer
I0829 12:45:29.952983   13818 clusterdeployer.go:236] Cleaning up bootstrap cluster.
F0829 12:45:29.953000   13818 create_cluster.go:63] unable to apply cluster api stack to bootstrap cluster: unable to apply cluster apiserver: unable to apply apiserver yaml: couldn't kubectl apply: exit status 1, output: error: error validating "STDIN": error validating data: ValidationError(APIService.spec): unknown field "priority" in io.k8s.kube-aggregator.pkg.apis.apiregistration.v1beta1.APIServiceSpec; if you choose to ignore these errors, turn validation off with --validate=false

After the fix is in place, this part passes without any other problem. We already have both versionPriority and groupPriority, so I believe we don't need any other change.

I have tested with both external cluster version 1.11, 1.12 (current master), 1.10, and Minikube 1.10.

Release note:

Remove priority field from the APIService manifest to make it compatible with 1.11+ bootstrap clusters.

[sttts]

/ok-to-test

[detiber]

/lgtm

@roberthbailey ptal

[roberthbailey]

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: roberthbailey, xmudrii

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 [roberthbailey]

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

[roberthbailey]

thanks for fixing this!