Adding a new unit in an existing cluster does not work - Postgres 14.11 rev 384

### Steps to Reproduce
1. Add a new PostgreSQL unit to an existing cluster using Juju:
```bash
juju add-unit postgresql
```

### Expected Behavior
The PostgreSQL processes on the new unit should start and run successfully.

### Actual Behavior
Instead, the PostgreSQL processes fail to start. Checking the syslog reveals that the folder **`/var/snap/charmed-postgresql/common/var/lib/postgresql`** has invalid permissions.

Manually changing the permissions of the folder to `750` and then running:
```bash
snap start postgresql
```
resolves the issue.

### Environment Details
- PostgreSQL: 14.11 (rev 384)
- OS: Ubuntu 22.04.5 LTS