Patroni Exporter broken dashboard panels

## Steps to reproduce
1. Deploy the charm.
2. Open the Patroni Grafana dashboard.

## Expected behaviour
Patroni panels (`xlog_location`, etc.) should render correctly.

## Actual behaviour
Panels show no data. Prometheus and the OpenMetrics standard now automatically append `_total` to the name of any metric with the TYPE `counter`. The dashboard queries still use the legacy metric names.

## Versions

Juju CLI: N/A
Juju agent: N/A
Charm revision: N/A
LXD: N/A

## Log output
Juju debug log: N/A

## Additional context
**Proposal:**
Patch the Grafana dashboard JSON to comply with the OpenMetrics standard by updating the following queries:
* `patroni_xlog_location` -> `patroni_xlog_location_total`
* `patroni_xlog_received_location` -> `patroni_xlog_received_location_total`
* `patroni_xlog_replayed_location` -> `patroni_xlog_replayed_location_total`