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