Logical replication creates infinite loop of inserts

## Steps to reproduce

1. juju deploy postgresql-k8s --channel 16/edge --trust postgresql1
2. juju deploy postgresql-k8s --channel 16/edge --trust postgresql2
3. juju deploy data-integrator di1 --config database-name=testdb
4. juju deploy data-integrator di2 --config database-name=testdb
5. juju integrate postgresql1 di1
6. juju integrate postgresql2 di2
7. juju integrate postgresql1:logical-replication-offer postgresql2:logical-replication
8. juju integrate postgresql1:logical-replication postgresql2:logical-replication-offer
9. juju run di1/leader get-credentials
10. psql `PSQL URI FROM ABOVE`
11. create table asd (message int);\q
12. juju run di2/leader get-credentials
13. psql `PSQL URI FROM ABOVE`
14. create table asd (message int);\q
15. juju config postgresql1 logical_replication_subscription_request='{"testdb": ["public.asd"]}'
16. juju config postgresql2 logical_replication_subscription_request='{"testdb": ["public.asd"]}'

## Expected behaviour
A blocked status message telling that the same table cannot be defined on both sides of the relation for the logical replication.

## Actual behaviour

An infinite loop of inserts happens due to the cyclic replication that was configured by configuring the same table on both sides of the relation.

## Versions

Operating system: Ubuntu 24.04

Juju CLI: 3.6.8

Juju agent: 3.6.8

Charm revision: 638

microk8s: 1.32-strict/stable

## Log output

Juju debug log: no relevant logs.

## Additional context

The table needs to be empty in both clusters; otherwise, the charm will properly set a blocked status indicating the table is not empty in one of the clusters.

This is the same situation as reported at https://github.com/canonical/postgresql-operator/issues/1085.

Reproduce the cycle using the listed Juju deployments, the logical-replication relations, and matching subscription requests for public.asd. Inspect the charm's logical-replication configuration and status handling; done means both applications report a blocked status explaining that the same table cannot be defined on both sides, instead of endlessly inserting.

Written by the indexing model from the issue text.