Don't forward .internal

### 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

The ICANN has decided to reserve the `.internal` TLD for private use applications. ([Source](https://www.icann.org/en/board-activities-and-meetings/materials/approved-resolutions-special-meeting-of-the-icann-board-29-07-2024-en#section2.a))

### Proposed solution

This means that any query involing a `.internal` domain shouldn't be forwarded to a public DNS server.

### Alternatives considered and additional information

Forwarding to an internal DNS server like the router should still be possible.