PG16-K8s cannot be deployed to Canonical K8s. Error: calling self.fix_leader_annotation() (PG14-K8s works)

## Steps to reproduce
1. Launch LXD with enough disk/CPU/RAM: `lxc launch --vm ubuntu:24.04 -c limits.cpu=12 -c limits.memory=32GiB -d root,size=200GiB myc8s`
2. Deploy Canonical K8s inside newly started VM using https://canonical-charmed-postgresql-k8s.readthedocs-hosted.com/16/how-to/deploy/canonical-k8s/
3. try to deploy PG16: `juju deploy postgresql-k8s --channel 16/edge --trust` (r613 is failing). PG14 woks well (r495)!

## Expected behavior
PG16 deployed without errors

## Actual behavior
Charm stuck in `awaiting for cluster to start`:
```
root@2xenrico:~# juju status
Model Controller Cloud/Region Version SLA Timestamp
test16 ck8s ck8s 3.6.7 unsupported 16:35:03Z

App Version Status Scale Charm Channel Rev Address Exposed Message
postgresql-k8s 16.9 waiting 1 postgresql-k8s 16/edge 613 10.152.183.219 no awaiting for cluster to start

Unit Workload Agent Address Ports Message
postgresql-k8s/0* waiting executing 10.1.0.172 awaiting for cluster to start
```

## Versions

Operating system: 24.04
Juju CLI: 3.6.7
Juju agent: 3.6.7
Charm revision: postgresql-k8s 16/edge r613
Canonical K8s: k8s v1.32.5 3581 1.32-classic/stable canonical✓ classic

## Log output
```
unit-postgresql-k8s-0: 16:42:03 DEBUG unit.postgresql-k8s/0.juju-log ops 2.22.0 up and running.
unit-postgresql-k8s-0: 16:42:03 WARNING unit.postgresql-k8s/0.juju-log /var/lib/juju/agents/unit-postgresql-k8s-0/charm/src/charm.py:220: DeprecationWarning: JujuVersion.from_environ() is deprecated, use self.model.juju_version instead
unit-postgresql-k8s-0: 16:42:03 DEBUG unit.postgresql-k8s/0.juju-log no relation on 'tracing': tracing not ready
unit-postgresql-k8s-0: 16:42:03 DEBUG unit.postgresql-k8s/0.juju-log Starting root trace with id='b46b424fd89d9f9b71781b7ed3d9761a'.
unit-postgresql-k8s-0: 16:42:03 DEBUG unit.postgresql-k8s/0.juju-log Re-emitting deferred event via PostgresqlOperatorCharm/on/postgresql_pebble_ready[26]>.
unit-postgresql-k8s-0: 16:42:03 DEBUG unit.postgresql-k8s/0.juju-log Building PostgreSQL parameters for profile='production' and available_memory=33541885952
unit-postgresql-k8s-0: 16:42:03 INFO unit.postgresql-k8s/0.juju-log Updating Patroni config file
unit-postgresql-k8s-0: 16:42:04 DEBUG unit.postgresql-k8s/0.juju-log Early exit update_config: Workload not started yet
unit-postgresql-k8s-0: 16:42:04 INFO unit.postgresql-k8s/0.juju-log Updated health checks
unit-postgresql-k8s-0: 16:42:04 DEBUG unit.postgresql-k8s/0.juju-log Starting new HTTP connection (1): postgresql-k8s-0.postgresql-k8s-endpoints:8008
unit-postgresql-k8s-0: 16:42:05 DEBUG unit.postgresql-k8s/0.juju-log Starting new HTTP connection (1): postgresql-k8s-0.postgresql-k8s-endpoints:8008
unit-postgresql-k8s-0: 16:42:06 DEBUG unit.postgresql-k8s/0.juju-log Starting new HTTP connection (1): postgresql-k8s-0.postgresql-k8s-endpoints:8008
unit-postgresql-k8s-0: 16:42:07 DEBUG unit.postgresql-k8s/0.juju-log Starting new HTTP connection (1): postgresql-k8s-0.postgresql-k8s-endpoints:8008
unit-postgresql-k8s-0: 16:42:08 DEBUG unit.postgresql-k8s/0.juju-log Starting new HTTP connection (1): postgresql-k8s-0.postgresql-k8s-endpoints:8008
unit-postgresql-k8s-0: 16:42:09 DEBUG unit.postgresql-k8s/0.juju-log Starting new HTTP connection (1): postgresql-k8s-0.postgresql-k8s-endpoints:8008
unit-postgresql-k8s-0: 16:42:10 DEBUG unit.postgresql-k8s/0.juju-log Starting new HTTP connection (1): postgresql-k8s-0.postgresql-k8s-endpoints:8008
unit-postgresql-k8s-0: 16:42:11 DEBUG unit.postgresql-k8s/0.juju-log Starting new HTTP connection (1): postgresql-k8s-0.postgresql-k8s-endpoints:8008
unit-postgresql-k8s-0: 16:42:12 DEBUG unit.postgresql-k8s/0.juju-log Starting new HTTP connection (1): postgresql-k8s-0.postgresql-k8s-endpoints:8008
unit-postgresql-k8s-0: 16:42:13 DEBUG unit.postgresql-k8s/0.juju-log Starting new HTTP connection (1): postgresql-k8s-0.postgresql-k8s-endpoints:8008
unit-postgresql-k8s-0: 16:42:14 DEBUG unit.postgresql-k8s/0.juju-log Starting new HTTP connection (1): postgresql-k8s-0.postgresql-k8s-endpoints:8008
unit-postgresql-k8s-0: 16:42:14 DEBUG unit.postgresql-k8s/0.juju-log Deferring on_postgresql_pebble_ready: Waiting for cluster to start
unit-postgresql-k8s-0: 16:42:14 DEBUG unit.postgresql-k8s/0.juju-log Deferring via PostgresqlOperatorCharm/on/postgresql_pebble_ready[26]>.
unit-postgresql-k8s-0: 16:42:14 DEBUG unit.postgresql-k8s/0.juju-log Re-emitting deferred event .
unit-postgresql-k8s-0: 16:42:14 DEBUG unit.postgresql-k8s/0.juju-log Defer on_config_changed: cluster not initialised yet
unit-postgresql-k8s-0: 16:42:14 DEBUG unit.postgresql-k8s/0.juju-log Deferring .
unit-postgresql-k8s-0: 16:42:14 DEBUG unit.postgresql-k8s/0.juju-log Re-emitting deferred event via PostgresqlOperatorCharm/on/database_peers_relation_changed[71]>.
unit-postgresql-k8s-0: 16:42:14 DEBUG unit.postgresql-k8s/0.juju-log Starting new HTTP connection (1): postgresql-k8s-primary.test16.svc.cluster.local:8008
unit-postgresql-k8s-0: 16:42:15 DEBUG unit.postgresql-k8s/0.juju-log Starting new HTTP connection (1): postgresql-k8s-primary.test16.svc.cluster.local:8008
unit-postgresql-k8s-0: 16:42:16 DEBUG unit.postgresql-k8s/0.juju-log Starting new HTTP connection (1): postgresql-k8s-primary.test16.svc.cluster.local:8008
unit-postgresql-k8s-0: 16:42:17 DEBUG unit.postgresql-k8s/0.juju-log Starting new HTTP connection (1): postgresql-k8s-primary.test16.svc.cluster.local:8008
unit-postgresql-k8s-0: 16:42:18 DEBUG unit.postgresql-k8s/0.juju-log Starting new HTTP connection (1): postgresql-k8s-primary.test16.svc.cluster.local:8008
unit-postgresql-k8s-0: 16:42:19 DEBUG unit.postgresql-k8s/0.juju-log Starting new HTTP connection (1): postgresql-k8s-primary.test16.svc.cluster.local:8008
unit-postgresql-k8s-0: 16:42:20 DEBUG unit.postgresql-k8s/0.juju-log Starting new HTTP connection (1): postgresql-k8s-primary.test16.svc.cluster.local:8008
unit-postgresql-k8s-0: 16:42:21 DEBUG unit.postgresql-k8s/0.juju-log Starting new HTTP connection (1): postgresql-k8s-primary.test16.svc.cluster.local:8008
unit-postgresql-k8s-0: 16:42:22 DEBUG unit.postgresql-k8s/0.juju-log Starting new HTTP connection (1): postgresql-k8s-primary.test16.svc.cluster.local:8008
unit-postgresql-k8s-0: 16:42:23 DEBUG unit.postgresql-k8s/0.juju-log Starting new HTTP connection (1): postgresql-k8s-primary.test16.svc.cluster.local:8008
unit-postgresql-k8s-0: 16:42:24 DEBUG unit.postgresql-k8s/0.juju-log Starting new HTTP connection (1): postgresql-k8s-primary.test16.svc.cluster.local:8008
unit-postgresql-k8s-0: 16:42:24 DEBUG unit.postgresql-k8s/0.juju-log Deferring on_postgresql_pebble_ready: Waiting for primary endpoint to be ready
unit-postgresql-k8s-0: 16:42:24 DEBUG unit.postgresql-k8s/0.juju-log Deferring via PostgresqlOperatorCharm/on/database_peers_relation_changed[71]>.
unit-postgresql-k8s-0: 16:42:24 DEBUG unit.postgresql-k8s/0.juju-log _initialized_cluster failed on _peer_relation_changed
unit-postgresql-k8s-0: 16:42:24 DEBUG unit.postgresql-k8s/0.juju-log Emitting Juju event update_status.
unit-postgresql-k8s-0: 16:42:24 DEBUG unit.postgresql-k8s/0.juju-log pgdata free disk space: 1003884544 out of 1020702720, ratio of 0.9835229438792913
unit-postgresql-k8s-0: 16:42:24 ERROR unit.postgresql-k8s/0.juju-log calling self.fix_leader_annotation()
unit-postgresql-k8s-0: 16:42:24 DEBUG unit.postgresql-k8s/0.juju-log on_update_status early exit: Unit is in Blocked/Waiting status
unit-postgresql-k8s-0: 16:42:24 INFO juju.worker.uniter.operation ran "update-status" hook (via hook dispatching script: dispatch)
```

Start with the Canonical K8s deployment steps and the charm log around self.fix_leader_annotation(), then compare the failing PostgreSQL 16 deployment with the working PostgreSQL 14 case. Reproduce the reported deployment using the listed Juju, charm, and Kubernetes versions; done means PostgreSQL 16 reaches a running cluster instead of waiting for the cluster to start.

Written by the indexing model from the issue text.