No logging or compaction enabled for logs in snap internal /var/log/ folders

## Steps to reproduce

1. Setup charmed-postgresql, connect an application to generate data. Deploying the default landscape-scalable bundle would be a good way to start generating logs.

## Expected behavior
I expect the internal /var/log/ folder to start compacting old logs and eventually rotating them. I would like charm or snap level config knobs to alter this behavior (ie rotate logs after x days, keep logging directory under x GB, etc).

## Actual behavior

files just build up in var/log/.


## Versions

Operating system: 22.04.5 LTS

Juju CLI: 3.5.4

Juju agent: 3.5.0

Charm revision: 429

LXD: 5.0.3

Reproduce the issue by deploying charmed-postgresql, generating application data, and inspecting the internal /var/log/ folders while using the reported Ubuntu, Juju, agent, charm, and LXD versions. Trace how the snap or charm handles those logs and identify the relevant configuration entry points. Done means old logs are compacted or rotated and the requested retention or size controls are available and verified.

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