Configure inhibit/silence rule for instance_size_dependent label before enabling azure_postgres_connections_high alert

Context

The azure_postgres_connections_high alert rule in python-pulumi/src/ptd/grafana_alerts/azure_postgres.yaml is currently paused (isPaused: true). It must remain paused until two conditions are met:

1. An inhibit/silence rule for the instance_size_dependent: "true" label is configured in Alertmanager/Grafana OnCall, so small-SKU Postgres instances don't produce false positives.
2. This tracking issue URL is recorded in the YAML comment.

What needs to be done

• Configure an inhibit/silence rule that suppresses alerts with instance_size_dependent="true" for known small-SKU Postgres instances.
• Once the inhibit rule is in place, update the isPaused: true comment in azure_postgres.yaml with this issue URL and unpause the alert.

Related file

python-pulumi/src/ptd/grafana_alerts/azure_postgres.yaml, rule uid: azure_postgres_connections_high

A test in python-pulumi/tests/test_azure_alert_files.py guards against accidental unpausing.

Start with python-pulumi/src/ptd/grafana_alerts/azure_postgres.yaml and the rule with UID azure_postgres_connections_high, then review python-pulumi/tests/test_azure_alert_files.py. Configure the Alertmanager/Grafana OnCall suppression for instance_size_dependent="true", record this issue URL in the YAML comment, unpause the rule, and run the test to verify it.