Failed to start Service for snap application charmed-postgresql.prometheus-postgres-exporter

## Steps to reproduce
sudo snap restart charmed-postgresql.prometheus-postgres-exporter

## Expected behavior
The service shoud be restarted

## Actual behavior
It fails.

## Versions

tracking: 14/stable
hold: forever
installed: 14.13 (133) 186MB disabled,held

Operating system: Ubuntu 22.04.4 LTS

Juju CLI: 3.6.8-genericlinux-amd64

Juju agent:
version: 3.6.4

Charm revision:
429

LXD: 5.X stable

## Log output

Juju debug log:

## Additional context
This started to happen out of the blue. We then tried restarting the node-exporter as described, but this doesn't work.

Start by reproducing `sudo snap restart charmed-postgresql.prometheus-postgres-exporter` on the reported Ubuntu 22.04.4 system with charm revision 429, then inspect the service failure and collect the missing Juju debug log. Done means identifying why the exporter service fails to restart and verifying that it starts successfully.

Written by the indexing model from the issue text.