Adguard 8.0 excessive disk usage upon startup by service process

### Please answer the following questions for yourself before submitting an issue

- [x] Filters were updated before reproducing an issue
- [x] I checked the [knowledge base](https://adguard.com/kb/) and found no answer
- [x] I checked to make sure that this issue has not already been filed

### AdGuard version

8.0.5143.0

### Browser version

irrelevant

### OS version

Windows 10 19045

### Traffic filtering

- [x] yes, I do

### Ad Blocking

AdGuard Base filter

### Privacy

AdGuard Tracking Protection filter

### Language-specific

AdGuard Russian filter

### Which DNS server do you use?

System default DNS

### DNS protocol

Regular

### Custom DNS

_No response_

### What Stealth Mode options do you have enabled?

Send Do-Not-Track header

### Issue Details

Steps to reproduce:
1. Start operating system or restart AdGuardSvc
2. Observe anomalous system disk usage, and adguard database files being repeatedly open and closed

### Expected Behavior

Adguard service does not cause excessive disk usage

### Actual Behavior

AdGuardSvc causes excessive disk usage for from 20 seconds to up to 3 minutes


### Additional Information

Very likely should be fixed by switching all SQLite database files into WAL mode (currently only adguard.db is in WAL mode, statistics.db and certs.db are in `JOURNAL DELETE`, afaik), and not closing "connection" to them during lifetime of AdguardSvc (this one should help a lot)