Automatic merge from submit-queue (batch tested with PRs 50087, 39587, 50042, 50241, 49914)

Enable selfHosted feature flag

**What this PR does / why we need it**:

Enables feature gating for self-hosting on kubeadm

**Which issue this PR fixes**

Continuation of https://github.com/kubernetes/kubeadm/issues/323

**Release note**:
```release-note
Feature gates now determine whether a cluster is self-hosted. For more information, see the FeatureGates configuration flag.
```

/cc @luxas