Automatic merge from submit-queue (batch tested with PRs 67756, 64149, 68076, 68131, 68120). If you want to cherry-pick this change to another branch, please follow the instructions here: https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md.

kube-ctrl-mgr: enable secure port 10257

This PR enables authn+authz (delegated to the kube-apiserver) and the secure port 10257 for the kube-controller-manager. In addition, the insecure port is disabled.

Moreover, it adds integration test coverage for the `--port` and `--secure-port` flags, plus the testserver infrastructure to tests flags in general inside integration tests.

```release-note
Enable secure serving on port 10257 to kube-controller-manager (configurable via `--secure-port`). Delegated authentication and authorization have to be configured like for aggregated API servers.
```