Optimistic Cache - Disabling/Re-Enabling without WAN freezes AGH

### 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 report a bug and not ask a question

### Operating system type

Linux, OpenWrt

### CPU architecture

64-bit ARM

### Installation

GitHub releases or script from README

### Setup

On one machine

### AdGuard Home version

Latest Edge

### Description

Running the latest AGH Edge build on Raspberry Pi 4 ARM64 Bullseye.

Problem:
- Disabling (and re-enabling) Optimistic Cache when not connected to WAN results in AGH hanging/freezing for 10-15 seconds and network connection errors popping up before the setting kicks in.

Note:
- A similar issue (reported by me) existed for other AGH settings, but was re-produced by AGH developers resolved a while back.

Question:
- Where does AGH store Optimistic Cache data? Can it deleted manually? Is it encrypted? I hope its not possible for someone to just open it up and poison it.