Upstream latency increase since v0.107.55

### 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

GitHub releases or script from README

### Setup

On one machine

### AdGuard Home version

0.107.55

### Action

Replace the following command with the one you're calling or a
description of the failing action:

```sh
N/A
```

### Expected result

Upstream latency should be in line with my ISP WAN connection (FTTP/fibre), approx 12ms.

### Actual result

Since upgrading to 0.107.55 the upstream latency has drifted, a fair amount. I am aware that the release is intended to address latency issues (eg #6818), ironically.

On previous versions (eg 0.107.54) my upstream latency across 24 hours is approximately 12ms-14ms for most upstreams. After upgrading to 0.107.55 the upstreams are between 17ms and 32ms. I have verified this multiple times, on the same home LAN with the same clients and (roughly) the same type of traffic. I have tested on my primary LAN DNS server (bare metal, Radxa Rock5B, Debian Bookworm aarch64), and also confirmed the same issue on my backup instance (Alpine Linux LXC on Proxmox, AMD Ryzen x86_64 host).

Downgrading to 0.107.54 immediately fixes the issue, and upstream latency returns to around 12ms. I have pprof running, and can switch versions and/or collect stats and logs as required. Many thanks in advance.

### Additional information and/or screenshots

Here is a redacted copy of the AdGuardHome.yaml (extension changed to .txt for Github).
[AdGuardHome.txt](https://github.com/user-attachments/files/18203481/AdGuardHome.txt)