Patroni dashboard has no filtering for juju model

## Steps to reproduce

1. Install charm and relate it to cos
2. Open patroni dashboard

## Expected behavior
See information from only one cluster, and be able to filter clusters by juju model

## Actual behavior
See the mix of data from all cluster which is not very useful, also juju model shows even models without postgres

## Versions

Operating system:

Juju CLI: 3.6.14

Juju agent: 3.6.14

Charm revision: 1047 and 1158

LXD: N/A

## Log output

Juju debug log: N/A

## Additional context

Start by installing the charm, relating it to COS, and opening the Patroni dashboard to reproduce the mixed-cluster view. Trace the dashboard data and filtering entry points; done means one selected Juju model is shown and models without PostgreSQL are excluded.

Written by the indexing model from the issue text.