Suppress / Disable pedantic DDR certificate warnings

### Prerequisites

- [x] I have checked the [Wiki](https://github.com/AdguardTeam/AdGuardHome/wiki) and [Discussions](https://github.com/AdguardTeam/AdGuardHome/discussions) and found no answer

- [x] I have searched other issues and found no duplicates

- [x] I want to request a feature or enhancement and not ask a question

### The problem

Right now, AdGuard Home logs the following warning on startup when using a publicly signed certificate (e.g., Let's Encrypt / ZeroSSL wildcard) for local encryption:
validating certificate pair: certificates has no IP addresses; DNS-over-TLS won't be advertised via DDR
On a private RFC 1918 network (192.168.x.x / 10.x.x.x), public CAs will never issue certificates containing private IP SANs. However, opportunistic DDR client auto-discovery works seamlessly across modern operating systems (iOS, macOS, Chrome, Firefox) using domain-based SVCB/HTTPS records.
The current behavior leaves users with a permanent "broken" warning for a setup that is working as intended, with no way to satisfy the warning without breaking DDR or setting up a custom internal CA.

### Proposed solution

Add a UI toggle under Settings → Encryption to enable/disable or suppress DDR warnings.
Demote this log entry from a warning to an DEBUG or INFO level message, as it flags a standard RFC limitation rather than an actionable configuration error.

### Alternatives considered and additional information

_No response_