DNS upstream returned reply with wrong number of answers

### Prerequisites

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

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

- [x] I want to report a bug and not [ask a question or ask for help](https://github.com/AdguardTeam/AdGuardHome/discussions/categories/q-a)

- [x] I have set up AdGuard Home correctly and [configured clients to use it](https://github.com/AdguardTeam/AdGuardHome/wiki/Clients). (Use the [Discussions](https://github.com/AdguardTeam/AdGuardHome/discussions/categories/q-a) for help with installing and configuring clients.)

### Platform (OS and CPU architecture)

Linux, ARM64

### Installation

Docker

### Setup

On one machine

### AdGuard Home version

v0.107.66

### Action

Hello,

I have an Adguard Home instance running which I use for DoH which is working perfectly fine for my already connected devices via the Adguard app with a custom DNS server (my Adguard Home instance).

I'm tried to add DoH in combination with my Adguard Home instance to more devices (iOS) via the Adguard app.

### Expected result

In the Adguard app I'd expect to be able to create a custom DNS server with the URL of my Adguard Home instance and be able to connect to it like it worked before on other devices.

### Actual result

However if I try to add another device via the Adguard app as I did on my other devices some time ago or try to add the Adguard Home server to an already working device with a modified client id in the url, I get the error 'You have entered an invalid upstream' when I click the button 'Save And Select.

Exporting the (debug) logs of this try to add a new server reveals the following error log:
```
[995543(NewDnsServerController.dnsCheckQueue)] (DnsProvidersManager) - addCustomProvider; Trying to add custom provider with name=Test1, upstreams=https:////dns-query/ selectAsCurrent=true
[995543(NewDnsServerController.dnsCheckQueue)] (NetworkUtils) - upstreamIsValid; Error: Error Domain=com.adguard.dnsproxy Code=13 "Error at ag::dns::test_upstream_internal:54: DNS upstream returned reply with wrong number of answers" UserInfo={NSLocalizedDescription=Error at ag::dns::test_upstream_internal:54: DNS upstream returned reply with wrong number of answers}
```

At the moment I have no idea what might have been changed which would explain why I cannot add my Adguard Home instance to new devices anymore (existing devices with the mentioned config are working without any problems).

### Additional information and/or screenshots

_No response_