Resolution AAAA-records only if A-record is unavaible

### 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

I can't find a feature for AdGuard to resolve a domain name to an IPv6 address, only if the IPv4 address is unavailable.
My situation is that my ISP doesn't offer the IPv6 protocol. I access the internet via IPv4, but I have a VPN provider that allows me to access the IPv6 network. I'd like clients to access the internet via the IPv4 protocol and my primary ISP, and only if they can't access the website via IPv4 (since the website only has an AAAA record) should they connect to the website via IPv6. I was able to configure IPv4 routing through the ISP and IPv6 routing through the VPN provider, but clients with IPv6 prefer to access the website via IPv6. Unfortunately, the VPN provider's exit point is in another country, and some local sites don't allow connections from abroad or from IP addresses belonging to VPN providers.
I couldn't think of anything else to do other than truncate AAAA responses when an A record is present.

### Proposed solution

Add the ability to disable IPv6-address resolving when IPv4 addresses are present.

### Alternatives considered and additional information

_No response_