Automatic merge from submit-queue (batch tested with PRs 41901, 50762, 50756)
Feature-gate self-hosted secrets
**What this PR does / why we need it**:
Feature gates now select whether secrets are used for TLS cert storage in self-hosted clusters.
**Release note**:
```release-note
TLS cert storage for self-hosted clusters is now configurable. You can store them as secrets (alpha) or as usual host mounts.
```
/cc @luxas
4a15d32bec